miR-638 suppresses cell proliferation in gastric cancer by targeting Sp2

Identifying Specificity Protein 2 as a key marker for diabetic encephalopathy in the context of predictive, preventive, and personalized medicine

Background

Transcription factor specificity protein (SP2) regulates various cellular functions, including cell division, proliferation, invasion, metastasis, differentiation, and death; however, its role has not been studied in prominent medical conditions including diabetic encephalopathy (DE). Therefore, this study addressed its physiological function in the context of DE to also better characterize its possible use in the context of predictive, preventive, and personalized medicine (PPPM).

Methods

The anti-inflammatory and anti-DE actions of SP2 were investigated using three animal models (SP2-/- mice, streptozocin-treated mice, and db/db mice) and two cell lines (primary cultured hippocampal neurons and N2A cells). The db/db mice were a leptin deficiency model often used to study type 2 diabetes. An equal number of males and females (8-12 weeks of age) was selected. Behavioral changes in mice were determined using both morris water maze (MWM) test and Y-maze (YM) test. The alterations in oxidative stress and inflammation were examined via immunofluorescence assay, flow cytometry, co-immunoprecipitation, and immunoblotting.

Results

Mechanistically, SP2-knockout (SP2-/-) mice showed dysregulation of insulin/glucose homeostasis, neuroinflammation, and cognitive loss. Otherwise, in db/db DE mice and STZ-induced DE mice, neuroinflammation, neuroapoptosis, and cognitive decline were significantly attenuated when SP2 was overexpressed in the brain. On the other hand, SP2 overexpression activates the insulin signaling pathway and improves insulin resistance via targeting X-box binding protein 1 (XBP1) in neurons. Moreover, SP2 overexpression significantly reduces oxidative stress by interacting with XBP1 and nuclear factor erythroid 2-related factor 2 (NRF2) in neurons. Furthermore, SP2 enhances the suppression of inflammatory response triggered by nuclear factor kappa B (NFκB) through the recruitment of XBP1 and NRF2 and by the in vitro inactivation of IκB kinase (IKK) complex.

Conclusions

These findings highlight SP2 as key biological targets for DE and reveal the infammation-related potential molecular mechanism of DE, which is helpful for early risk prediction and targeted prevention of DE. In conclusion, our study provides a new perspective for developing a PPPM method for managing DE patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00394-0.

The function of long non-coding RNA SNHG11 and its working mechanism in triple-negative breast cancer

Triple-negative breast cancer (TNBC) seriously affects woman's health. The present work is to study the working mechanism of lncRNA SNHG11 in TNBC. The expressions of SNHG11, microRNA (miR)- 7-5p, specificity protein 2 (SP2) and mucin 1 (MUC-1) in TNBC tissues and cells were detected. SNHG11, miR-7-5p and SP2 expressions were then evaluated for TNBC cell malignant behaviors. The relationships among SNHG11, miR-7-5p and SP2 were predicted and verified. Finally, the binding of the transcription factor SP2 to MUC-1 promoter was detected. Abnormally elevated SNHG11, SP2 and MUC-1 expressions were observed in cultured TNBC cells and tumor tissues. SNHG11 knockdown in TNBC cells. Silencing SP2 weakened the promoting effect of SNHG11 on TNBC progression. SNHG11 negatively regulated miR-7-5p expression and positively regulated SP2 expression. SP2 bound to the P2 site of MUC-1 promoter, and SP2 knockdown suppressed MUC-1 expression. It was demonstrated that lncRNA SNHG11 promoted TNBC cell malignant behaviors to facilitate TNBC progression. The study is first of its kinds to unravel the potential of lncRNA SNHG11 in relation to TNBC.

Specificity Proteins (Sp) and Cancer

The specificity protein (Sp) transcription factors (TFs) Sp1, Sp2, Sp3 and Sp4 exhibit structural and functional similarities in cancer cells and extensive studies of Sp1 show that it is a negative prognostic factor for patients with multiple tumor types. In this review, the role of Sp1, Sp3 and Sp4 in the development of cancer and their regulation of pro-oncogenic factors and pathways is reviewed. In addition, interactions with non-coding RNAs and the development of agents that target Sp transcription factors are also discussed. Studies on normal cell transformation into cancer cell lines show that this transformation process is accompanied by increased levels of Sp1 in most cell models, and in the transformation of muscle cells into rhabdomyosarcoma, both Sp1 and Sp3, but not Sp4, are increased. The pro-oncogenic functions of Sp1, Sp3 and Sp4 in cancer cell lines were studied in knockdown studies where silencing of each individual Sp TF decreased cancer growth, invasion and induced apoptosis. Silencing of an individual Sp TF was not compensated for by the other two and it was concluded that Sp1, Sp3 and Sp4 are examples of non-oncogene addicted genes. This conclusion was strengthened by the results of Sp TF interactions with non-coding microRNAs and long non-coding RNAs where Sp1 contributed to pro-oncogenic functions of Sp/non-coding RNAs. There are now many examples of anticancer agents and pharmaceuticals that induce downregulation/degradation of Sp1, Sp3 and Sp4, yet clinical applications of drugs specifically targeting Sp TFs are not being used. The application of agents targeting Sp TFs in combination therapies should be considered for their potential to enhance treatment efficacy and decrease toxic side effects.

The functions and molecular mechanisms of Tribbles homolog 3 (TRIB3) implicated in the pathophysiology of cancer

Currently, cancer ranks as the second leading cause of death worldwide, and at the same time, the burden of cancer continues to increase. The underlying molecular pathways involved in the initiation and development of cancer are the subject of considerable research worldwide. Further understanding of these pathways may lead to new cancer treatments. Growing data suggest that Tribble's homolog 3 (TRIB3) is essential in oncogenesis in many types of cancer. The mammalian tribbles family's proteins regulate various cellular and physiological functions, such as the cell cycle, stress response, signal transduction, propagation, development, differentiation, immunity, inflammatory processes, and metabolism. To exert their activities, Tribbles proteins must alter key signaling pathways, including the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K)/AKT pathways. Recent evidence supports that TRIB3 dysregulation has been linked to various diseases, including tumor development and chemoresistance. It has been speculated that TRIB3 may either promote or inhibit the onset and development of cancer. However, it is still unclear how TRIB3 performs this dual function in cancer. In this review, we present and discuss the most recent data on the role of TRIB3 in cancer pathophysiology and chemoresistance. Furthermore, we describe in detail the molecular mechanism TRIB3 regulates in cancer.

miR-638: A Promising Cancer Biomarker with Therapeutic Potential

BACKGROUND

There is an unmet need to improve the diagnosis of cancer with precise treatment strategies. Therefore, more powerful diagnostic, prognostic, and therapeutic biomarkers are needed to overcome tumor cells. microRNAs (miRNAs, miRs), as a class of small non-coding RNAs, play essential roles in cancer through the tumor-suppressive or oncogenic effects by post-transcriptional regulation of their targets. Many studies have provided shreds of evidence on aberrantly expressed miRNAs in numerous cancers and have shown that miRNAs could play potential roles as diagnostic, prognostic, and even therapeutic biomarkers in patients with cancers. Findings have revealed that miR-638 over or underexpression might play a critical role in cancer initiation, development, and progression. However, the mechanistic effects of miR-638 on cancer cells are still controversial.

CONCLUSION

In the present review, we have focused on the diagnostic, prognostic, and therapeutic potentials of miR-638 and discussed its mechanistic roles in various types of cancers.

Comprehensive analyses of the microRNA-messenger RNA-transcription factor regulatory network in mouse and human renal fibrosis

Objective: The aim of this study was to construct a microRNA (miRNA)-messenger RNA (mRNA)-transcription factor (TF) regulatory network and explore underlying molecular mechanisms, effective biomarkers, and drugs in renal fibrosis (RF). Methods: A total of six datasets were downloaded from Gene Expression Omnibus. "Limma" and "DESeq2" packages in R software and GEO2R were applied to identify the differentially expressed miRNAs and mRNAs (DEmiRNAs and DEmRNAs, respectively). The determination and verification of DEmiRNAs and DEmRNAs were performed through the integrated analysis of datasets from five mouse 7 days of unilateral ureteral obstruction datasets and one human chronic kidney disease dataset and the Human Protein Atlas (http://www.proteinatlas.org). Target mRNAs of DEmiRNAs and TFs were predicted by prediction databases and the iRegulon plugin in Cytoscape, respectively. A protein-protein interaction network was constructed using STRING, Cytoscape v3.9.1, and CytoNCA. Functional enrichment analysis was performed by DIANA-miRPath v3.0 and R package "clusterProfiler." A miRNA-mRNA-TF network was established using Cytoscape. Receiver operating characteristic (ROC) curve analysis was used to examine the diagnostic value of the key hub genes. Finally, the Comparative Toxicogenomics Database and Drug-Gene Interaction database were applied to identify potential drugs. Results: Here, 4 DEmiRNAs and 11 hub genes were determined and confirmed in five mouse datasets, of which Bckdha and Vegfa were further verified in one human dataset and HPA, respectively. Moreover, Bckdha and Vegfa were also predicted by miR-125a-3p and miR-199a-5p, respectively, in humans as in mice. The sequences of miR-125a-3p and miR-199a-5p in mice were identical to those in humans. A total of 6 TFs were predicted to regulate Bckdha and Vegfa across mice and humans; then, a miRNA-mRNA-TF regulatory network was built. Subsequently, ROC curve analysis showed that the area under the curve value of Vegfa was 0.825 (p = 0.002). Finally, enalapril was identified to target Vegfa for RF therapy. Conclusion: Pax2, Pax5, Sp1, Sp2, Sp3, and Sp4 together with Bckdha-dependent miR-125a-3p/Vegfa-dependent miR-199a-5p formed a co-regulatory network enabling Bckdha/Vegfa to be tightly controlled in the underlying pathogenesis of RF across mice and humans. Vegfa could act as a potential novel diagnostic marker and might be targeted by enalapril for RF therapy.

Novel biomarkers of microRNAs in gastric cancer; an overview from diagnosis to treatment

The fourth frequent disease in the world and the second cause of cancer-related death is gastric cancer (GC). In this way, over 80% of diagnoses are made in the middle to advanced degrees of the disease, underscoring the requirement for innovative biomarkers that can be identified quickly. Meaningly, biomarkers that can complement endoscopic diagnosis and be used to detect patients with a high risk of GC are desperately needed. These biomarkers will allow for the accurate prediction of therapy response and prognosis in GC patients, as well as the development of an optimal treatment strategy for each individual. Conspicoiusly, microRNAs (miRNAs) and small noncoding RNA regulates the expression of target mRNA and thereby modifies critical biological mechanisms. According to the data, abnormally miRNAs expression in GC is linked to tumor growth, carcinogenesis, aggression and distant metastasis. Importantly, miRNA expression patterns and next-generation sequencing (NGS) can also be applied to analyze kinds of tissues and cancers. Given the high death rates and poor prognosis of GC, and the absence of a clinical diagnostic factor that is adequately sensitive to GC, research into novel sensitive and specific markers for GC diagnosis is critical. In this review,we evaluate the latest research findings that suggest the feasibility and clinical utility of miRNAs in GC.

miR-638 suppresses proliferation by negatively regulating high mobility group A1 in ovarian cancer cells

Ovarian cancer is one of the most common gynecological diseases with high mortality rates. Previous studies have shown that microRNA (miR)-638 is associated with tumorigenesis. The present study aimed to assess the role and underlying mechanisms of miR-638 in ovarian cancer. miR-638 expression was detected in ovarian cancer tissues and miR-638 was overexpressed or knocked down in ovarian cancer OVCAR-3 and Caov-3 cells. The clinical results revealed that miR-638 expression was downregulated in ovarian cancer tissues compared with in adjacent normal tissues. miR-638 expression was also found to be relatively low in OVCAR-3 cells whilst being relatively high in Caov-3 cells among the five ovarian cancer cell lines tested. miR-638 overexpression inhibited cell viability, arrested the cell cycle at the G₁ phase and promoted apoptosis in OVCAR-3 cells. By contrast, miR-638 knockdown increased Caov-3 cell viability, facilitated cell cycle progression and inhibited apoptosis. miR-638 reduced the expression of high mobility group A1 (HMGA1) by directly targeting its 3' untranslated region. HMGA1 overexpression reversed the inhibition of proliferation induced by miR-638 overexpression in OVCAR-3 cells. These results suggest that miR-638 may serve to be a suppressor of ovarian cancer by regulating HMGA1, which may provide a potential therapeutic target for ovarian cancer.

Src-1 and SP2 promote the proliferation and epithelial-mesenchymal transition of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is characterized by high morbidity and morality, especially in Southern China. Transcription factors intensively participate in the initiation and development of NPC. This study aimed to investigate the roles of Src-1 in NPC. mRNA level was determined by qRT-PCR. Western blot was carried out for the protein level. CCK-8 assay was performed to determine cell viability, colony formation for NPC cell proliferation, and transwell for cell migration and invasion ability. The results showed Steroid receptor coactivator 1 (Src-1) was overexpressed in SNE-2 and 6-10B. The expression of Src-1 and SP2 was in positive correlation. Overexpression of Src-1 promoted the cell viability, colony formation, and epithelial-mesenchymal transition (EMT), manifested by the increase of migration and invasion ability, while knockdown of Src-1 exerted opposite effects. Additionally, knockdown or overexpression of SP2 reversed the effects of overexpressed or downregulated Src-1, which was reversed by the depletion of SP2. Moreover, Src-1 interacted with SP2 to regulate EMT-related genes such as E-cad, N-cad, Vimentin, and ZEB1, and proliferation- and apoptosis-related genes, such as bax, cytochrome c, and cleaved caspase3 and bcl-2. Thus, blocking the interaction between Src-1 and SP2 may be a therapeutic target for inhibiting the metastasis of NPC.

ANLN, Regulated by SP2, Promotes Colorectal Carcinoma Cell Proliferation via PI3K/AKT and MAPK Signaling Pathway

BACKGROUND

Aberrant expression of Anillin (ANLN) has been shown to function in the development of multiple cancers. However, its effects on colorectal carcinoma (CRC) remain unclear. We aimed to explore the role of ANLN in CRC development.

METHODS

By real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, and immunohistochemistry (IHC), we assessed the expression level of ANLN in CRC tissues and cell lines. The role of ANLN in CRC cell proliferation was evaluated by CCK-8 assays, colony formation assays, EdU assays and cell cycle assays. A mouse tumorigenic model was established to evaluate the in vivo function of ANLN.

RESULTS

We found that ANLN was overexpressed in CRC tissues and cell lines. Highly expressed ANLN correlated with tumor size, tumor number, and stage in patients with CRC. Silencing ANLN in CRC cell lines suppressed proliferation both in vitro and in vivo and induced G0/G1 cell cycle arrest. Downregulation of ANLN led to reduced phosphorylated levels of AKT and ERK. However, total AKT protein showed no change. SP2, a critical transcription factor, was implicated in the upregulation of ANLN.

CONCLUSIONS

Our study demonstrated that ANLN regulates CRC cell proliferation via the PI3K/AKT and MAPK pathways, indicating that ANLN may represent a novel and effective target for CRC treatment.

HNRNPD interacts with ZHX2 regulating the vasculogenic mimicry formation of glioma cells via linc00707/miR-651-3p/SP2 axis

Studies have found that RNA-binding proteins (RBPs) are dysfunctional and play a significant regulatory role in the development of glioma. Based on The Cancer Genome Atlas database and the previous studies, we selected heterogeneous nuclear ribonucleoprotein (HNRNPD) as the research candidate and sought its downstream targeted genes. In the present study, HNRNPD, linc00707, and specific protein 2 (SP2) were highly expressed, while zinc fingers and homeboxes 2 (ZHX2) and miR-651-3p were remarkedly downregulated in glioma tissues and cells. HNRNPD, linc00707, and SP2 knockdown or ZHX2 and miR-651-3p overexpression suppressed glioma cells proliferation, migration, and invasion and vasculogenic mimicry (VM) formation. Knockdown of HNRNPD increased the stability of ZHX2 mRNA. ZHX2 bound to the promoter region of linc00707 and negatively regulate its expression. Linc00707 could bind with miR-651-3p, while miR-651-3p bound to the 3' untranslated region (3'UTR) of SP2 mRNA to negatively regulate its expression. The transcription factor SP2 directly bound to the promoter regions of the VM formation-related proteins MMP2, MMP9, and VE-cadherin, playing a role in promoting transcription in order to regulate the VM formation ability of glioma cells.

MicroRNA-638 induces apoptosis and autophagy in human liver cancer cells by targeting enhancer of zeste homolog 2 (EZH2)

Liver cancer is of the devastating human cancers and its incidence is increasing at an alarming rate. The clinical outcomes are far from descent due to lack of efficient therapeutic targets and chemotherapeutic agents. Studies have revealed the therapeutic implications of microRNAs in the management of different human cancers. This study was designed to explore the role and therapeutic potential of miR-638 in liver cancer via modulation of zeste homolog 2 (EZH2). The results revealed significant (P < 0.05) downregulation of miR-638 in human liver cancer tissues and cell lines. Overexpression of miR-638 led to a significant (P < 0.05) decline in liver cancer cell proliferation. Nonetheless, inhibition of miR-638 could promote the proliferation of the human liver cancer cells. The DAPI and annexin V/PI staining assays revealed that miR-638 induces apoptosis in human liver cancer cells which was accompanied by enhancement of Bax and depletion of Bcl-2 expression. Furthermore, miR-638 overexpression also leads to a significant (P < 0.05) increase of autophagosomes and autolysosomes in liver cancer cells suggestive of autophagy. The induction of autophagy was further confirmed by increase and decrease in expression of LC3B-II and Beclin-1 proteins, respectively. In contrary, inhibition of miR-638 prevented both apoptosis and autophagy of the liver cancer cells. In silico analysis and the dual luciferase assay revealed EZH2 as the molecular target of miR-638 at post-transcriptional level. The qRT-PCR showed that EZH2 to be significantly (P < 0.05) upregulated in the human liver cancer tissues and cell lines. However, the expression of EZH2 was considerably suppressed upon miR-638 overexpression in SNU-423 cells. Taken together, these findings suggest the tumor-suppressive role of miR-638/EZH2 axis liver cancer and point towards the potential of miR-638 as therapeutic target in the treatment of liver cancer.

Dysregulation of miR-638 in the progression of cancers

MicroRNA (miRNA) is a form of short, single-stranded and non-coding RNA that is important in regulating the post-transcriptional modification of multiple downstream targets. Many miRNAs have been reported to involve in controlling the progression of human diseases, and one of them is miR-638, which play essential roles in regulating the development of human cancer. By targeting the 3'-ends of its targets, miR-638 can regulate cellular processes including proliferation, invasion, metastases, angiogenesis, apoptosis and inflammation. This review was aimed to summarize current findings on the roles of miR-638 in different human cancers based on the results from various in vitro, in vivo and clinical studies. The biogenesis process and tissue expression, followed by the roles of miR-638 in regulating the development of various human cancers by targeting different downstream targets were covered in this review. The potential applications and challenges of employing miR-638 as cancer biomarker and therapeutic agent were also discussed.

Exosomes Released from CaSR-Stimulated PMNs Reduce Ischaemia/Reperfusion Injury

Ischemia-reperfusion (I/R) injury caused by acute myocardial infarction (AMI) can initiate a strong inflammatory response. Polymorphonuclear cells (PMNs) are the most important inflammatory cells. Our previous studies found that the calcium-sensing receptor (CaSR) regulates the proinflammatory effects of PMNs. However, the role and mechanism of CaSR-regulated PMNs in I/R injury remain uncertain. A rat AMI model was developed in this study and showed that the expression of CaSR on PMNs increased in AMI; however, the levels of Bcl-xl and SOD in myocardial tissue decreased, while Bax and MDA levels increased. Then, after coculture with CaSR-stimulated PMNs, the expression of Bcl-xl in cardiomyocytes significantly increased, Bax expression and the apoptotic rate decreased, and ROS production was significantly inhibited. At the same time, the cardiomyocyte damage caused by hypoxia-reoxygenation was reduced. Furthermore, we found that exosomes derived from PMNs could be taken up by cardiomyocytes. Additionally, the exosomes secreted by CaSR-stimulated PMNs had the same effect on cardiomyocytes as CaSR-stimulated PMNs, while the increased phosphorylation level of AKT in cardiomyocytes could be revered by AKT transduction pathway inhibitors. Subsequently, we identified the exosomes derived from CaSR-stimulated PMNs by second-generation sequencing technology, and increased expression of lncRNA ENSRNOT00000039868 was noted. The data show that this lncRNA can prevent the hypoxia-reoxygenation injury by upregulating the expression of PDGFD in cardiomyocytes. In vivo, exosomes from CaSR-stimulated PMNs played a significant role against AMI and reperfusion injury in myocardial tissue. Thus, we propose that exosomes derived from CaSR-stimulated PMNs can reduce I/R injury in AMI, and this effect may be related to the AKT signaling pathway.

Sp2 promotes invasion and metastasis of hepatocellular carcinoma by targeting TRIB3 protein

Objective

To explore the biological function and molecular mechanism of Sp2 in hepatocellular carcinoma (HCC).

Methods

Tissue microarray immunohistochemistry and western blot were used to study the expression of Sp2 in hepatocellular tissue and adjacent non‐neoplastic tissues (ANT). In HCC cell lines, the role of Sp2 was determined by in vitro experiments such as CCK8, clone formation test, Transwell assay, wound‐healing assay, and flow cytometry apoptotic analysis, and its possible mechanism was analyzed.

Results

Compared with ANT, Sp2 expression in HCC tissues was significantly up‐regulated, which was strongly associated with stage of tumor and poor prognosis of patients. TCGA database were further confirmed these results. Besides, functional studies had shown that Sp2 knockdown not only leads to a decrease in cell proliferation and an increase in cell apoptosis but also inhibits the cells' abilities of migration and invasion. Sp2 silencing could inhibit the expression of TRIB3 protein and down‐regulate the endoplasmic reticulum stress (ERS) level of HCC.

Conclusion

Sp2 may play a part in promoting cancer by regulating TRIB3 protein, which may be a factor of prognostic and a potential new therapeutic target for HCC.

miR-638 acts as an oncogene and predicts poor prognosis in renal cell carcinoma

OBJECTIVE

The aim of this study was to investigate the function and prognostic value of miR-638 in renal cell carcinoma (RCC).

METHODS

Expression of miR-638 in RCC tissues and corresponding noncancerous tissues were examined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). To explore the effects of miR-638 on cell migration, invasion, viability, and apoptosis of RCC cells, wound scratch, transwell, MTT, CCK-8, and flow cytometry assays were performed. Kaplan-Meier and Cox regression analyses were used to evaluate the relationship between miR-638 expression and prognosis of RCC patients. Potential target genes of miR-638 were predicted and validated via multiple bioinformatics analyses.

RESULTS

miR-638 was upregulated in RCC tissues when compared with corresponding noncancerous tissues (P < 0.05). Upregulation of miR-638 expression by transfection with a synthetic miR-638 mimic promoted cell migration, invasion, and viability and suppressed cell apoptosis. Moreover, Kaplan-Meier analysis revealed that upregulation of miR-638 associated with shorter overall survival (OS; P = 0.001). Cox univariate and multivariate regression analysis suggested that miR-638 expression is an independent predictive factor for the prognosis of RCC patients (P = 0.004). KCNQ1, DNAJC6, and PNP were identified as potential target genes of miR-638.

CONCLUSIONS

The results of this study demonstrated that miR-638 functions as an oncogene in RCC and has the potential to be a prognostic biomarker for RCC.

Upregulated expression of G9a is correlated with poor prognosis of gastric cancer patients

As one of the most serious cancers, gastric cancer (GC) represents the third leading cause of malignancy-related deaths. G9a is a histone lysine methyltransferase and has been reported to be involved in the progression of some human cancers. In the present study, we aimed to explore the expression patterns and clinical value of G9a in GC patients.The expression of G9a in 142 paired GC tissues and adjacent non-cancerous tissues (no less than 5 cm from tumor edge) was examined with quantitative real-time polymerase chain reaction (qRT-PCR). To estimate the association of G9a expression with clinical characteristics of GC patients, Chi-square test and t test were conducted. Kaplan-Meier survival and multivariate Cox regression analyses were performed to explore the prognostic value of G9a in GC.Upregulated expression of G9a was found in GC tissues compared with noncancerous tissues (P < .001). Elevated G9a expression was significantly correlated with patients' lymph node metastasis (P = .007) and TNM stage (P < .001). Kaplan-Meier survival curves demonstrated that patients with high G9a expression had shorter survival time than those with low expression (log-rank test, P < .05), reaching a median OS of 24 months. According to the results of Cox regression, G9a could be considered as an independent prognostic biomarker in patients with GC (HR = 3.912, 95% CI = 2.213-6.915, P < .001). Additionally, the diagnosis cut-off value of G9a in GC patients was 1.515.Taken together, G9a expression was upregulated in GC tissues and could be an effective prognostic biomarker for GC.

miR-638 represses the stem cell characteristics of breast cancer cells by targeting E2F2

OBJECTIVE

The miR-638 acted as a tumor suppressor and E2F transcription factor 2 (E2F2) was a critical regulator in some cancers, while the role of them on stemness of breast cancer stem cells (BCSCs) was rarely detailed. Hence, we focused on exploring the effects of miR-638 and E2F2 on BCSCs stemness.

METHODS

The proportion of CD24 -/CD44 + cells of BCSCs was detected by flow cytometry. The target relationship of miR-638 and E2F2 was explored using luciferase assays. The ability of self-renewal, proliferation, and invasion of BCSCs were determined by Mammosphere forming, Cell Counting Kit-8 (CCK-8), colony formation, and transwell assays. Xenograft tumor was established to detect the influence of miR-638 on tumor growth.

RESULTS

miR-638 was down-regulated, while E2F2 was elevated in breast cancer. The E2F2 level was negatively correlated with miR-638. The BCSCs represented higher proportion of CD24 -/CD44 + cells and levels of sex determining region Y-box 2 (SOX2) and octamer-binding transcription factor 4 (OCT4). The miR-638 was down-regulated and E2F2 was increased in BCSCs. MiR-638 could target to E2F2 and decreased the level of E2F2 in BCSCs cells. Overexpression of miR-638 decreased the proportion of CD24 -/CD44 + cells and the levels of SOX2 and OCT4 by inhibiting E2F2. The overexpression of miR-638 also inhibited the abilities of self-renewal, proliferation, and invasion of BCSCs by inhibiting E2F2. The miR-638 overexpression inhibited the breast tumor growth.

CONCLUSION

MiR-638 represses the characteristics and behaviors of BCSCs by targeting E2F2. MiR-638 may be a potential target for breast cancer therapy.

MicroRNA-638 inhibits human aortic valve interstitial cell calcification by targeting Sp7

Calcific aortic valve disease (CAVD) is a complex heart valve disease involving a wide range of pathological changes. Emerging evidence indicates that osteogenic differentiation of human aortic valve interstitial cells (hAVICs) plays a key role in valve calcification. In this study, we aimed to investigate the function of miR-638 in hAVICs osteogenesis. Both miRNA microarray assay and qRT-PCR results demonstrating miR-638 was obviously up-regulated in calcific aortic valves compared with non-calcific valves. We also proved that miR-638 was significantly up-regulated during hAVICs osteogenic differentiation. Overexpression of miR-638 suppressed osteogenic differentiation of hAVICs in vitro, whereas down-regulation of miR-638 enhance the process. Target prediction analysis and dual-luciferase reporter assay confirmed that Sp7 transcription factor (Sp7) was a direct target of miR-638. Furthermore, knockdown of Sp7 inhibited osteogenic differentiation of hAVICs, which is similar to the results observed in up-regulation miR-638. Our data indicated that miR-638 plays an inhibitory role in hAVICs osteogenic differentiation, which may act by targeting Sp7. MiR-638 may be a potential therapeutic target for CAVD.

A mathematical model as a tool to identify microRNAs with highest impact on transcriptome changes

Background

Rapid changes in the expression of many messenger RNA (mRNA) species follow exposure of cells to ionizing radiation. One of the hypothetical mechanisms of this response may include microRNA (miRNA) regulation, since the amounts of miRNAs in cells also vary upon irradiation. To address this possibility, we designed experiments using cancer-derived cell lines transfected with luciferase reporter gene containing sequences targeted by different miRNA species in its 3′- untranslated region. We focus on the early time-course response (1 h past irradiation) to eliminate secondary mRNA expression waves.

Results

Experiments revealed that the irradiation-induced changes in the mRNA expression depend on the miRNAs which interact with mRNA. To identify the strongest interactions, we propose a mathematical model which predicts the mRNA fold expression changes, caused by perturbation of microRNA-mRNA interactions. Model was applied to experimental data including various cell lines, irradiation doses and observation times, both ours and literature-based. Comparison of modelled and experimental mRNA expression levels given miRNA level changes allows estimating how many and which miRNAs play a significant role in transcriptome response to stress conditions in different cell types. As an example, in the human melanoma cell line the comparison suggests that, globally, a major part of the irradiation-induced changes of mRNA expression can be explained by perturbed miRNA-mRNA interactions. A subset of about 30 out of a few hundred miRNAs expressed in these cells appears to account for the changes. These miRNAs play crucial roles in regulatory mechanisms observed after irradiation. In addition, these miRNAs have a higher average content of GC and a higher number of targeted transcripts, and many have been reported to play a role in the development of cancer.

Conclusions

Our proposed mathematical modeling approach may be used to identify miRNAs which participate in responses of cells to ionizing radiation, and other stress factors such as extremes of temperature, exposure to toxins, and drugs.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5464-0) contains supplementary material, which is available to authorized users.

MicroRNA-770 affects proliferation and cell cycle transition by directly targeting CDK8 in glioma

Background

MicroRNAs play crucial roles in tumorigenesis and tumor progression. miR-770 has been reported to be downregulated in several cancers and affects cancer cell proliferation, apoptosis, metastasis and drug resistance. However, the role and underlying molecular mechanism of miR-770 in human glioma remain unknown and need to be further elucidated.

Methods

The expression of miR-770 in glioma tissues and cell lines was measured by quantitative real-time PCR (qRT-PCR) to explore the association of miR-770 expression with clinicopathological characteristics. The expression of CDK8 was detected by qRT-PCR and Western blotting in glioma tissues. A target prediction program and a dual-luciferase reporter assay were used to confirm that CDK8 is a target gene of miR-770. MTT and cell counting assays were used to assess the effect of miR-770 on glioma cell proliferation. The cell cycle distribution and apoptosis were examined by flow cytometry. CDK8 siRNA and overexpression were used to further confirm the function of the target gene.

Results

We demonstrated that miR-770 expression was downregulated in human glioma tissues and cell lines. The overexpression of miR-770 inhibited glioma cell proliferation and cell cycle G1-S transition and induced apoptosis. The inhibition of miR-770 facilitated cell proliferation and G1-S transition and suppressed apoptosis. miR-770 expression was inversely correlated with CDK8 expression in glioma tissues. CDK8 was confirmed to be a direct target of miR-770 by using a luciferase reporter assay. The overexpression of miR-770 decreased CDK8 expression at both the mRNA and protein levels, and the suppression of miR-770 increased CDK8 expression. Importantly, CDK8 silencing recapitulated the cellular and molecular effects observed upon miR-770 overexpression, and CDK8 overexpression eliminated the effects of miR-770 overexpression on glioma cells. Moreover, both exogenous expression of miR-770 and silencing of CDK8 resulted in suppression of the Wnt/β-catenin signaling pathway.

Conclusions

Our study demonstrates that miR-770 inhibits glioma cell proliferation and G1-S transition and induces apoptosis through suppression of the Wnt/β-catenin signaling pathway by targeting CDK8. These findings suggest that miR-770 plays a significant role in glioma progression and serves as a potential therapeutic target for glioma.

MicroRNA-1254 exerts oncogenic effects by directly targeting RASSF9 in human breast cancer

MicroRNAs (miRNAs or miRs) play crucial roles in human breast cancer. Although miR-1254 has been shown to have oncogenic activity in several cancer types, its biological function in breast cancer and its mechanisms of action remain unclear. In this study, we investigated the role of miR-1254 in human breast cancer and sought to elucidate the relevant underlying mechanisms. We found that miR-1254 expression was markedly increased in breast cancer tissues and cell lines. Additionally, miR-1254 overexpression accelerated breast cancer cell proliferation, cell cycle G1-S phase transition and inhibited apoptosis. Nevertheless, the inhibition of miR-1254 suppressed cell proliferation and induced apoptosis. Further analyses revealed that miR-1254 expression negatively correlated with RASSF9 expression in breast cancer tissues. We verified that RASSF9 was a direct target of miR-1254 using a luciferase reporter assay. The overexpression of miR-1254 reduced the RASSF9 mRNA and protein levels, and the suppression of miR-1254 promoted RASSF9 expression. Notably, the knockdown or overexpression of RASSF9 corroborated the biological effects observed upon miR-1254 overexpression or inhibition. Taken together, these results demonstrate that miR-1254 accelerates breast cancer cell growth by activating the AKT signaling pathway and suppresses apoptosis by inhibiting p53 expression through the targeting of RASSF9. The data indicate that miR-1254 plays a crucial role in human breast cancer, and may represent a novel therapeutic target for this malignancy.

MicroRNA-638 inhibits human airway smooth muscle cell proliferation and migration through targeting cyclin D1 and NOR1

Abnormal airway smooth muscle cell (ASMC) proliferation and migration contribute significantly to increased ASM mass associated with asthma. MicroRNA (miR)-638 is a primate-specific miRNA that plays important roles in development, DNA damage repair, hematopoiesis, and tumorigenesis. Although it is highly expressed in ASMCs, its function in ASM remodeling remains unknown. In the current study, we found that in response to various mitogenic stimuli, including platelet-derived growth factor-two B chains (PDGF-BB), transforming growth factor β1, and fetal bovine serum, the expression of miR-638, as determined by quantitative real-time polymerase chain reaction (qRT-PCR), was significantly downregulated in the proliferative human ASMCs. Both gain- and loss-of-function studies were performed to study the role of miR-638 in ASMC proliferation and migration. We found that adenovirus-mediated miR-638 overexpression markedly inhibits ASMC proliferation and migration, while ablation of miR-638 by anti-miR-638 markedly increases cell proliferation and migration, as determined by WST-8 proliferation and scratch wound assays. Dual-luciferase reporter assay, qRT-PCR, and immunoblot analysis were used to investigate the effects of miR-638 on the expression of the downstream target genes in ASMCs. Our results demonstrated that miR-638 overexpression significantly reduced the expression of downstream target cyclin D1 and NOR1, both of which have been shown to be essential for cell proliferation and migration. Together, our study provides the first in vitro evidence highlighting the antiproliferative and antimigratory roles of miR-638 in human ASMC remodeling and suggests that targeted overexpression of miR-638 in ASMCs may provide a novel therapeutic strategy for preventing ASM hyperplasia associated with asthma.

The microRNA expression signature of CD4+ T cells in the transition of brucellosis into chronicity

Brucellosis is a serious infectious disease that continues to be a significant cause of morbidity worldwide and across all ages. Despite early diagnosis and treatment, 10–30% of patients develop chronic brucellosis. Although there have been recent advances in our knowledge of Brucella virulence factors and hosts’ immune response to the infection, there is a lack of clear data regarding how the infection bypasses the immune system and becomes chronic. The present study investigated immunological factors and their roles in the transition of brucellosis from an acute to a chronic infection in CD4+ T cells. CD4+ T cells sorted from peripheral blood samples of patients with acute or chronic brucellosis and healthy controls using flow cytometry as well as more than 2000 miRNAs were screened using the GeneSpring GX (Agilent) 13.0 miRNA microarray software and were validated using reverse transcription polymerase chain reaction (RT-qPCR). Compared to acute cases, the expression levels of 28 miRNAs were significantly altered in chronic cases. Apart from one miRNA (miR-4649-3p), 27 miRNAs were not expressed in the acute cases (p <0.05, fold change> 2). According to KEGG pathway analysis, these miRNAs are involved in the regulation of target genes that were previously involved in the MAPK signalling pathway, regulation of the actin cytoskeleton, endocytosis, and protein processing in the endoplasmic reticulum. This indicates the potential role of these miRNAs in the development of chronic brucellosis. We suggest that these miRNAs can be used as markers to determine the transition of the disease into chronicity. This is the first study of miRNA expression that analyses human CD4+ T cells to clarify the mechanism of chronicity in brucellosis.

microRNA-3129 promotes cell proliferation in gastric cancer cell line SGC7901 via positive regulation of pRb

Several microRNAs (miRNAs) have been reported as oncogenes or tumor suppressors in many cancers, including gastric cancer (GC). However, the role and molecular mechanism of miR-3129 in GC is largely unknown. We aimed to explore the function and the underlying molecular mechanism of miR-3129 in GC. Cancer tissues and corresponding adjacent tissues were collected from 50 patients with GC, and the expression of miR-3129 was detected by RT-qPCR. The expression of miR-3129 and pRb in human GC cell line SCG7091 was altered by transient transfection. Thereafter, MTT and flow cytometry assays were used to analyze cell viability and cell cycle. The expression of cyclin E, CDK2, CDK2 inhibitors (p16 and 21), and pRb were detected by RT-qPCR and western blot. A significant up-regulation of miR-3129 was observed in GC tissues compared to adjacent tissues. Overexpression of miR-3129 significantly improved cell viability after 4 days of post-transfection. Flow cytometry assay results showed that the miR-3129 overexpression arrested more SGC7901 cells at S phase. Moreover, overexpression of miR-3129 down-regulated the expression of CDK2 inhibitors while it up-regulated the expression levels of cyclin E, CDK2, and pRb. Interestingly, we found that pRb inhibition reversed the effect of miR-3129 inhibitor on cell proliferation in SGC7901 cells, increased cell viability, reduced cells at G0/1 phase, and modulated the expression of proliferation-related factors. Our results revealed that miR-3129 functioned as an oncogene through positive regulation of pRb and may prove to be a promising option for molecular therapy of GC.

Minority stress and leukocyte gene expression in sexual minority men living with treated HIV infection

Sexual minority (i.e., non-heterosexual) individuals experience poorer mental and physical health, accounted for in part by the additional burden of sexual minority stress occurring from being situated in a culture favoring heteronormativity. Informed by previous research, the purpose of this study was to identify the relationship between sexual minority stress and leukocyte gene expression related to inflammation, cancer, immune function, and cardiovascular function. Sexual minority men living with HIV who were on anti-retroviral medication, had viral load < 200 copies/mL, and had biologically confirmed, recent methamphetamine use completed minority stress measures and submitted blood samples for RNA sequencing on leukocytes. Differential gene expression and pathway analyses were conducted comparing those with clinically elevated minority stress (n = 18) and those who did not meet the clinical cutoff (n = 20), covarying reactive urine toxicology results for very recent stimulant use. In total, 90 differentially expressed genes and 138 gene set pathways evidencing 2-directional perturbation were observed at false discovery rate (FDR) < 0.10. Of these, 41 of the differentially expressed genes and 35 of the 2-directionally perturbed pathways were identified as functionally related to hypothesized mechanisms of inflammation, cancer, immune function, and cardiovascular function. The neuroactive-ligand receptor pathway (implicated in cancer development) was identified using signaling pathway impact analysis. Our results suggest several potential biological pathways for future work investigating the relationship between sexual minority stress and health.

Extract of Stellerachamaejasme L(ESC) inhibits growth and metastasis of human hepatocellular carcinoma via regulating microRNA expression

BACKGROUND

MicroRNAs(miRNAs)are involved in the initiation and progression of hepatocellular carcinoma. ESC, an extract of Stellerachamaejasme L, had been confirmed as a potential anti-tumor extract of Traditional Chinese Medicine. In light of the important role of miRNAs in hepatocellular carcinoma, we questioned whether the inhibitory effects of ESC on hepatocellular carcinoma (HCC) were associated with miRNAs.

METHODS

The proliferation inhibition of ESC on HCC cells was measured with MTT assay. The migration inhibition of ESC on HCC cells was measured with transwell assay. The influences of ESC on growth and metastasis inhibition were evaluated with xenograft tumor model of HCC. Protein expressions were measured with western blot and immunofluorescence methods and miRNA profiles were detected with miRNA array. Differential miRNA and target mRNAs were verified with real-time PCR.

RESULTS

The results showed that ESC could inhibit proliferation and epithelial mesenchymal transition (EMT) in HCC cells in vitro and tumor growth and metastasis in xenograft models in vivo. miRNA array results showed that 69 differential miRNAs in total of 429 ones were obtained in MHCC97H cells treated by ESC. hsa-miR-107, hsa-miR-638, hsa-miR-106b-5p were selected to be validated with real-time PCR method in HepG2 and MHCC97H cells. Expressions of hsa-miR-107 and hsa-miR-638 increased obviously in HCC cells treated by ESC. Target genes of three miRNAs were also validated with real-time PCR. Interestingly, only target genes of hsa-miR-107 changed greatly. ESC downregulated the MCL1, SALL4 and BCL2 gene expressions significantly but did not influence the expression of CACNA2D1.

CONCLUSION

The findings suggested ESC regressed growth and metastasis of human hepatocellular carcinoma via regulating microRNAs expression and their corresponding target genes.

Expression of microRNA 638 and sex-determining region Y-box 2 in hepatocellular carcinoma: Association between clinicopathological features and prognosis

The aim of the present study was to determine the expression profile of microRNA 638 (miR-638) and sex-determining region Y-box 2 (SOX2) in hepatocellular carcinoma (HCC), and to investigate their association with clinicopathological features and survival. Reverse transcription-quantitative polymerase chain reaction analysis was used to investigate miR-638 and SOX2 expression in 78 patients with HCC. Western blot and immunohistochemical analyses were performed in order to determine SOX2 protein expression in HCC samples. Combined with the clinical postoperative follow-up data, the expression of miR-638 and SOX2 and the association between this and the prognostic values of patients with HCC were statistically analyzed. The results of the present study confirmed that miR-638 expression in tumor tissues was significantly downregulated (P<0.001), while SOX2 expression was significantly increased, compared with healthy control tissues (P<0.05). In addition, a significant inverse correlation between miR-638 and SOX2 expression was also observed in the HCC tissues (r=-0.675; P<0.05). Clinicopathological correlation analysis demonstrated that reduced miR-638 and elevated SOX2 expression was significantly associated with the Tumor-Node-Metastasis stage and portal vascular invasion (P<0.05). However, no significant differences were observed in other clinicopathological features, including age, sex, tumor size, tumor differentiation and hepatitis status (P>0.05). Notably, follow-up analysis revealed that patients with HCC with low miR-638 expression and high SOX2 expression tended to have a significantly shorter postoperative survival time (P<0.001). It was concluded that miR-638 may serve a vital role in the occurrence and progression of HCC by regulating SOX2 expression and thus, that miR-638 and SOX2 may be critical as novel diagnostic and prognostic biomarkers for HCC.

MicroRNA-638 inhibits cell growth and tubule formation by suppressing VEGFA expression in human Ewing sarcoma cells

Ewing sarcoma (EWS) is a kind of aggressive tumor of bone and soft tissues, which most occurring in children and adolescents. MicroRNAs (miRNAs) perform essential function in the progression and development of EWS, while the putative role of miR-638 in EWS remains uncertain. Accordingly, we detected the expression of miR-638 and explored its putative biological effects on the malignant phenotype of EWS cells. As expected, miR-638 was significantly down-regulated in EWS cells. Moreover, overexpression of miR-638 suppressed cell growth, induced cell apoptosis, and inhibited tubule formation of EWS cells in vitro Among the putative target genes of miR-638 predicted by the miRNA target prediction tools, vascular endothelial cell growth factor A (VEGFA) attracted out attention most. The luciferase reporter assays reaffirmed that VEGFA was a targeted gene of miR-638 in EWS cells. Furthermore, miR-638 suppressed the mRNA and protein level of VEGFA, and restored the expression of VEGFA reversed the suppressed effects of miR-638 in EWS cells. Taken together, the results suggested that miR-638 might perform tumor suppressive effects in EWS, which might be mediated, at least partially, through suppressing the activity of VEGFA.

MECP2 promotes the growth of gastric cancer cells by suppressing miR-338-mediated antiproliferative effect

The methyl-CpG-binding protein 2 (MECP2), a transcriptional suppressor, is involved in gene regulation by binding to methylated promoters. We found that MECP2 is overexpressed in gastric cancer (GC), and that Mecp2 knockdown affects the growth of GC cells both in vitro and in vivo. MECP2 can directly bind to the methylated-CpG island of miR-338 promoter and suppress the expression of two mature microRNAs, namely, miR-338-3p and miR-338-5p. Furthermore, miR-338-5p can suppress GC cell growth by targeting BMI1 (B lymphoma Mo-MLV insertion region 1 homolog). We additionally found that decreased miR-338-5p expression in GC tissues, relative to normal tissues, was significantly negatively correlated with increased BMI1 expression. Silencing MECP2 can indirectly lead to reduced expression of P-REX2, which has been identified as the miR-338-3p target, as well as BMI1 and increasing expression of P16 or P21 both in vitro and in vivo. Altogether, our results indicate that MECP2 promote the proliferation of GC cells via miR-338 (miR-338-3p and miR-338-5p)-mediated antitumor and gene regulatory effect.

miR-188 Inhibits Glioma Cell Proliferation and Cell Cycle Progression Through Targeting β-Catenin

MicroRNAs (miRNAs) play important roles in several human cancers. Although miR-188 has been suggested to function as a tumor repressor in cancers, its precise role in glioma and the molecular mechanism remain unknown. In the present study, we investigated the effect of miR-188 on glioma and explored its relevant mechanisms. We found that the expression of miR-188 is dramatically downregulated in glioma tissues and cell lines. Subsequent investigation revealed that miR-188 expression was inversely correlated with β-catenin expression in glioma tissue samples. Using a luciferase reporter assay, β-catenin was determined to be a direct target of miR-188. Overexpression of miR-188 reduced β-catenin expression at both the mRNA and protein levels, and inhibition of miR-188 increased β-catenin expression. Moreover, we found that overexpression of miR-188 suppressed glioma cell proliferation and cell cycle G₁–S transition, whereas inhibition of miR-188 promoted glioma cell proliferation. Importantly, silencing β-catenin recapitulated the cellular and molecular effects seen upon miR-188 overexpression, which included inhibiting glioma cell proliferation and G₁–S transition. Taken together, our results demonstrated that miR-188 inhibits glioma cell proliferation by targeting β-catenin, representing an effective therapeutic strategy for glioma.

MiR-638 acts as a tumor suppressor gene in gastric cancer

Gastric cancer is one of the major causes of cancer mortality. Several microRNAs play a role in the tumor growth and invasion. However, the underlying molecular mechanism remains poorly understood. We detected the miR-638 expression levels in tumor samples and adjacent noncancerous tissues from 68 patients with gastric cancer as well as in the gastric cancer cell line SGC-7901 and SC-M1. The cell cycle was analyzed by flow cytometry, cell proliferation was observed by CCK-8 assay and cell invasion was detected using Transwell assay. MiR-638 was down-regulated in human GC tissues and its expression level was negatively correlated to TNM stage and lymph metastasis. In the cell lines, aberrant expression of miR-638 was related to the cell proliferation, cell cycle and invasion. We also found that SOX2 had a negative correlation with miR-638 in GC tissues, and miR-638 overexpression could decrease SOX2 expression level by directly binding the 3’-UTR of SOX2. in vitro, down-regulating SOX2 by siRNA could counteract the effect of miR-638 inhibitor on GC cells proliferation and invasion. Our results demonstrate that miR-638 may play a pivotal role in the growth and invasion of GC.

miR-638 suppresses DNA damage repair by targeting SMC1A expression in terminally differentiated cells

The reduction of DNA damage repair capacity in terminally differentiated cells may be involved in sensitivity to cancer chemotherapy drugs; however, the underlying molecular mechanism is still not fully understood. Herein, we evaluated the role of miR-638 in the regulation of DNA damage repair in terminally differentiated cells. Our results show that miR-638 expression was up-regulated during cellular terminal differentiation and involved in mediating DNA damage repair processes. Results from a luciferase reporting experiment show that structural maintenance of chromosomes (SMC)1A was a potential target of miR-638; this was verified by western blot assays during cell differentiation and DNA damage induction. Overexpression of miR-638 enhanced the sensitivity of cancer cells to cisplatin, thus reducing cell viability in response to chemotherapy drug treatment. Furthermore, miR-638 overexpression affected DNA damage repair processes by interfering with the recruitment of the DNA damage repair-related protein, γH2AX, to DNA break sites. These findings indicate that miR-638 might act as a sensitizer in cancer chemotherapy and accompany chemotherapy drugs to enhance chemotherapeutic efficacy and to improve the chance of recovery from cancer.

MicroRNA expression in bone marrow-derived human multipotent Stromal cells

Background

Multipotent stromal cells (MSCs) are being studied in the field of regenerative medicine for their multi-lineage differentiation and immunoregulatory capacity. MicroRNAs (miRNAs) are short non-coding RNAs that are responsible for regulating gene expression by targeting transcripts, which can impact MSC functions such as cellular proliferation, differentiation, migration and cell death. miRNAs are expressed in MSCs; however, the impact of miRNAs on cellular functions and donor variability is not well understood. Eight MSC lines were expanded to passages 3, 5 and 7, and their miRNA expression was evaluated using microarray technology.

Results

Statistical analyses of our data revealed that 71 miRNAs out of 939 examined were expressed by this set of MSC lines at all passages and the expression of 11 miRNAs were significantly different between passages 3 and 7, while the expression of 7 miRNAs was significantly different between passages 3 and 5. The expression of these identified miRNAs was evaluated using RT-qPCR for both the first set of MSC lines (n = 6) and a second set of MSC lines (n = 7) expanded from passages 4 to 8. By RT-qPCR only 2 miRNAs, miR-638 and miR-572 were upregulated at passage 7 compared to passage 3 in the first set of MSC lines by 1.71 and 1.54 fold, respectively; and upregulated at passage 8 compared to passage 4 in the second set of MSC lines, 1.35 and 1.59 fold, respectively.

Conclusions

The expression of miR-638 and miR-572 can distinguish MSCs from two different passages of cell culture. These results may be useful in establishing critical quality attributes of MSCs and determining whether changes in these two miRNAs impact cellular functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3997-7) contains supplementary material, which is available to authorized users.

MeCP2, a target of miR-638, facilitates gastric cancer cell proliferation through activation of the MEK1/2-ERK1/2 signaling pathway by upregulating GIT1

Methyl-CpG binding protein 2 (MeCP2) is involved in the carcinogenesis and progression of multiple types of cancer. However, its precise role in gastric cancer (GC) and the relevant molecular mechanism remain unknown. In the present study, we found that miR-638 levels were lower in GC tissues and GC cell lines than in adjacent normal tissues and normal gastric epithelial cell lines, respectively. Low miR-638 levels were associated with poor tumor differentiation, tumor size and lymph node metastasis. MeCP2 expression levels were higher in GC tissues than in adjacent normal tissues. It was found that miR-638 inhibited GC cell proliferation, colony formation, G1–S transition and tumor growth, and induced cell apoptosis by directly targeting MeCP2. MeCP2 promoted GC cell proliferation, colony formation and G1–S cell-cycle transition, and suppressed apoptosis. Molecular mechanistic investigations were performed using an integrated approach with a combination of microarray analysis, chromatin immunoprecipitation sequencing and a reporter gene assay. The results showed that MeCP2 bound to the methylated CpG islands of G-protein-coupled receptor kinase-interacting protein 1 (GIT1) promoter and upregulated its expression, thereby activating the MEK1/2–ERK1/2 signaling pathway and promoting GC cell proliferation. Taken together, our study demonstrates that MeCP2, a target of miR-638, facilitates GC cell proliferation and induces cell-cycle progression through activation of the MEK1/2–ERK1/2 signaling pathway by upregulating GIT1. The findings suggest that MeCP2 plays a significant role in GC progression, and may serve as a potential target for GC therapy.

MiR-1202 functions as a tumor suppressor in glioma cells by targeting Rab1A

Aberrant expression of microRNAs correlates with the development and progression of human cancers by targeting downstream proteins. MiR-1202 is downregulated in ovarian cancer and clear cell papillary renal cell carcinoma; however, its role in glioma remains unknown. The purpose of this study was to determine the expression and the role of miR-1202 and to elucidate its regulatory mechanism in glioma. We used quantitative real-time polymerase chain reaction to measure miR-1202 expression in both glioma tissues and cell lines. The findings showed that the miR-1202 expression decreased dramatically in clinical glioma tissues and cell lines, and miR-1202 expression was inversely correlated with the expression of Rab1A. Using bioinformatics and luciferase reporter assays, we identified Rab1A as a novel and direct target of miR-1202. In vitro, overexpression of miR-1202 inhibited glioma cell proliferation and induced endoplasmic reticulum stress and apoptosis through targeting Rab1A, whereas suppression of miR-1202 promoted cell proliferation and inhibited endoplasmic reticulum stress and apoptosis. Similarly, silencing Rab1A with small interfering RNA also suppressed glioma cell growth and induced endoplasmic reticulum stress and apoptosis. Taken together, our data indicate that miR-1202 suppresses proliferation and induces endoplasmic reticulum stress and apoptosis through targeting and inhibiting Rab1A in glioma cells. These results suggest miR-1202 as a potential therapeutic target for the treatment of glioma patients.

SP and KLF Transcription Factors in Digestive Physiology and Diseases

Specificity proteins (SPs) and Krüppel-like factors (KLFs) belong to the family of transcription factors that contain conserved zinc finger domains involved in binding to target DNA sequences. Many of these proteins are expressed in different tissues and have distinct tissue-specific activities and functions. Studies have shown that SPs and KLFs regulate not only physiological processes such as growth, development, differentiation, proliferation, and embryogenesis, but pathogenesis of many diseases, including cancer and inflammatory disorders. Consistently, these proteins have been shown to regulate normal functions and pathobiology in the digestive system. We review recent findings on the tissue- and organ-specific functions of SPs and KLFs in the digestive system including the oral cavity, esophagus, stomach, small and large intestines, pancreas, and liver. We provide a list of agents under development to target these proteins.

Dysregulation of miR-638 in hepatocellular carcinoma and its clinical significance

MicroRNAs (miRNAs/miRs) have been identified as important post-transcriptional regulators in healthy liver physiology and liver diseases. However, the clinical significance of miR-638 in hepatocellular carcinoma (HCC) remains unclear. The aim of the present study was to investigate the status of miR-638 expression in HCC and to determine its clinical significance. The expression of miR-638 was evaluated in 60 HCC tissues samples and HCC SMMC-7721, HepG2 and Hep3B cell lines using reverse transcription-quantitative polymerase chain reaction. The association between the expression of miR-638 and the clinicopathological characteristics of patients with HCC was analyzed. The proportion of HCC patients with low miR-638 expression was identified as 68.3% (41/60). Furthermore, significantly lower miR-638 expression was identified in HCC tissue samples compared with the healthy control group (P=0.031). miR-638 expression was significantly lower in SMMC-7721 (P=0.021), HepG2 (P=0.005) and Hep3B (P=0.003) cells compared with the healthy human hepatic HL-7702 cell line. In addition, miR-638 expression was correlated with α-fetoprotein levels (P=0.042) and portal vein invasion (P=0.025). The area under curve was identified as 0.71 (95% confidence interval=0.63-0.79; P=0.001). The cut-off value for miR-638 was the median 2^-Δ∆Cq=0.125. In conclusion, miR-638 may be involved in the progression of HCC and act as a potential biomarker for the prediction of HCC.

MiR-34b-5p Suppresses Melanoma Differentiation-Associated Gene 5 (MDA5) Signaling Pathway to Promote Avian Leukosis Virus Subgroup J (ALV-J)-Infected Cells Proliferaction and ALV-J Replication

Avian leukosis virus subgroup J (ALV-J) is an oncogenic retrovirus that has a similar replication cycle to multiple viruses and therefore can be used as a model system for viral entry into host cells. However, there are few reports on the genes or microRNAs (miRNAs) that are responsible for the replication of ALV-J. Our previous miRNA and RNA sequencing data showed that the expression of miR-34b-5p was significantly upregulated in ALV-J-infected chicken spleens compared to non-infected chicken spleens, but melanoma differentiation-associated gene 5 (MDA5) had the opposite expression pattern. In this study, a dual-luciferase reporter assay showed that MDA5 is a direct target of miR-34b-5p. In vitro, overexpression of miR-34b-5p accelerated the proliferation of ALV-J-infected cells by inducing the progression from G2 to S phase and it promoted cell migration. Ectopic expression of MDA5 inhibited ALV-J-infected cell proliferation, the cell cycle and cell migration, and knockdown of MDA5 promoted proliferation, the cell cycle and migration. In addition, during ALV-J infections, MDA5 can detect virus invasion and it triggers the MDA5 signaling pathway. MDA5 overexpression can activate the MDA5 signaling pathway, and thus it can inhibit the mRNA and protein expression of the ALV-J env gene and it can suppress virion secretion. In contrast, in response to the knockdown of MDA5 by small interfering RNA (siRNA) or an miR-34b-5p mimic, genes in the MDA5 signaling pathway were significantly downregulated (P < 0.05), but the mRNA and protein expression of ALV-J env and the sample-to-positive ratio of virion in the supernatants were increased. This indicates that miR-34b-5p is able to trigger the MDA5 signaling pathway and affect ALV-J infections. Together, these results suggest that miR-34b-5p targets MDA5 to accelerate the proliferation and migration of ALV-J-infected cells, and it promotes ALV-J replication, via the MDA5 signaling pathway.

MicroRNA-638 inhibits cell proliferation by targeting suppress PIM1 expression in human osteosarcoma

MicroRNAs (miRNAs) are a type of small noncoding RNAs that often play important roles in carcinogenesis, but the carcinogenic mechanism of miRNAs is still unclear. This study will investigate the functions and the mechanism of miR-638 in osteosarcoma (OS). The expression of miR-638 in OS and the DNA copy number of miR-638 were detected by real-time PCR. The effect of miR-638 on cell proliferation was measured by CCK8 assay. Different assays, including bioinformatics algorithms, luciferase report assay, and Western blotting, were used to identify the target gene proviral integration site for Moloney murine leukemia virus 1 (PIM1) of miR-638 in OS. The expression of PIM1 in clinical OS tissues was also validated by immunohistochemical assay. From this research, we found that miR-638 was downregulated in OS tissues compared with corresponding noncancerous tissues (NCTs), and the DNA copy number of miR-638 was lower in OS than in NCTs, which may induce the corresponding downregulation of miR-638 in OS. Ectopic expression of miR-638 inhibited OS cell growth in vitro. Subsequently, we identified that PIM1 is the downstream target gene of miR-638 in OS cells, and silencing PIM1 expression phenocopied the inhibitory effect of miR-638 on OS cell proliferation. Furthermore, we observed that PIM1 was overexpressed in OS tissues, and high expression of PIM1 in OS predicted poor overall survival. In summary, we revealed that miR-638 functions as a tumor suppressor through inhibiting PIM1 expression in OS.

Loss of miR-638 promotes invasion and epithelial-mesenchymal transition by targeting SOX2 in hepatocellular carcinoma

Aberrant expression of microRNAs has been identified as regulators of biological processes of hepatocellular carcinoma (HCC) by negatively regulating protein-coding mRNAs. Several studies have demonstrated that miR-638 expression was dysregulated in various human cancers. However, the clinical significance and underlying mechanisms of miR-638 involved in HCC remain to be elucidated. Herein, we confirmed that a reduced miR-638 expression was present in HCC tissues and cell lines. Our clinical analysis revealed that the downregulated miR-638 expression was significantly correlated with poor prognostic features including high Edmondson-Steiner grade, venous infiltration and advanced tumor-node-metastasis (TNM) stage. Moreover, we demonstrated that miR-638 was a novel independent prognostic marker for predicting 5-year survival of HCC patients. Functionally, overexpressed miR-638 expression inhibited cell migration and invasion, while downregulated miR-638 reversed the effect. In addition, miR-638 could regulate SOX2 by directly binding to its 3'-UTR. Alternation of SOX2 expression at least partially abolished the migration and invasion effects of miR-638 on HCC cells. Aberrant miR-638 expression could regulate the expression level of epithelial-to-mesenchymal transition markers in vitro and in vivo by modulating SOX2 expression. In conclusion, our data indicated that miR-638 functioned as a tumor suppressor gene and play a critical role in the development of HCC.

miR-326 Inhibits Gastric Cancer Cell Growth Through Downregulating NOB1

MicroRNAs (miRNAs) play a crucial role in the development and progression of human cancers, including gastric cancer (GC). The discovery of miRNAs may provide a new and powerful tool for studying the mechanism, diagnosis, and treatment of GC. In this study, we aimed to investigate the role of miR-326 in the development and progression of GC. Quantitative PCR (qPCR) was used to measure the expression level of miR-326 in GC tissues and cell lines. We found that miR-326 was significantly downregulated during GC. In addition, overexpression of miR-326 inhibited GC cell proliferation. Fluorescence-activated cell sorting (FACS) further showed that miR-326 significantly induced GC cell G2/M arrest. Subsequent dual-luciferase reporter assay identified one of the proto-oncogene NOB1 as a direct target of miR-326, and NOB1 can save growth inhibition caused by miR-326. We also confirmed that the growth inhibition caused by miR-326 is associated with AKT pathway activation. Taken together, our results indicate that miR-326 could serve as a potential diagnostic biomarker and therapeutic option for GC in the near future.

Downregulation of miRNA-638 promotes angiogenesis and growth of hepatocellular carcinoma by targeting VEGF

The expression and function of microRNA-638 (miR-638) in hepatocellular carcinoma (HCC) remained unknown. Using the miRNA target prediction tools, we predicted that the vascular endothelial growth factor (VEGF) might be a direct target of miR-638. The aim of this study was to test the hypothesis that downregulation of miRNA-638 promotes angiogenesis and growth of HCC by targeting the VEGF signaling pathway. We found that miR-638 was significantly downregulated in HCC cells and clinical HCC specimens, and miR-638 levels were inversely correlated with tumor size, portal vein invasion and poor prognosis. Overexpression of miR-638 inhibited the processes of tumor angiogenesis in vitro and in vivo. The xenograft mouse model experiments showed miR-638 repressed tumor growth of HCC in vivo. Using a luciferase reporter assay, we identified VEGF as a direct target of miR-638. Subsequent investigation revealed that miR-638 expression was inversely correlated with VEGF expression in human HCC samples. Taken together, these results suggested that miR-638 is a novel therapeutic target for HCC and overexpression of miR-638 could suppress angiogenesis and tumor growth of HCC by inhibiting VEGF signaling.

Guanine-Rich Sequences Are a Dominant Feature of Exosomal microRNAs across the Mammalian Species and Cell Types

Exosome is an extracellular vesicle released from multivesicular endosomes and contains micro (mi) RNAs and functional proteins derived from the donor cells. Exosomal miRNAs act as an effector during communication with appropriate recipient cells, this can aid in the utilization of the exosomes in a drug delivery system for various disorders including malignancies. Differences in the miRNA distribution pattern between exosomes and donor cells indicate the active translocation of miRNAs into the exosome cargos in a miRNA sequence-dependent manner, although the molecular mechanism is little known. In this study, we statistically analyzed the miRNA microarray data and revealed that the guanine (G)-rich sequence is a dominant feature of exosome-dominant miRNAs, across the mammalian species-specificity and the cell types. Our results provide important information regarding the potential use of exosome cargos to develop miRNA-based drugs for the treatment of human diseases.

MiR-144 inhibits cell proliferation of renal cell carcinoma by targeting MTOR

MicroRNAs (miRNAs) modulate the expression of tumorigenesis-related genes and play important roles in the development of various types of cancers. It has been reported that miR-144 is dysregulated and involved in multiple malignant tumors, but its role in renal cell carcinoma (RCC) remains elusive. In this study, we demonstrated miR-144 was significantly downregulated in human RCC. The decreased miR-144 correlated with tumor size and TNM stage. Moreover, overexpression of miR-144 in vitro suppressed RCC cell proliferation and G2 transition, which were reversed by inhibition of miR-144. Bioinformatic analysis predicted that mTOR was a potential target of miR-144, which was further confirmed by dual luciferase reporter assay. Additionally, the examination of clinical RCC specimens revealed that miR-144 was inversely related to mTOR. Furthermore, knocking down mTOR with siRNA had the same biological effects as those of miR-144 overexpression in RCC cells, including cell proliferation inhibition and S/G2 cell cycle arrest. In conclusion, our results indicate that miR-144 affects RCC progression by inhibiting mTOR expression, and targeting miR-144 may act as a novel strategy for RCC treatment.

Clinical significance of expression of miR-638 in gastric carcinoma

AIM: To investigate the expression of miR-638 in gastric carcinoma and to analyze its clinical significance.

METHODS: Total RNA was extracted from 31 pairs of gastric carcinoma tissues and normal tissues. The expression levels of miR-638 were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The relationship between miR-638 expression and clinicopathological parameters of gastric carcinoma was analyzed.

RESULTS: miR-638 was lowly expressed in 27 (87.10%) cases of gastric carcinoma, and highly expressed in 4 (12.90%) cases. The expression level of miR-638 was significantly lower in gastric carcinoma tissues than in normal tissues (P < 0.01). miR-638 expression in gastric carcinoma was significantly associated with the depth of tumor invasion (P < 0.05), but was not associated with sex, age, degree of differentiation, TNM stage, or lymph node metastasis (P > 0.05).

CONCLUSION: The expression of miR-638 is lower than in normal tissues in gastric carcinoma, which may be associated with the carcinogenesis and development of gastric carcinoma.

Are Circulating microRNAs Involved in Tumor Surveillance?

By studying literature data and having performed an in silico analysis, the circulating microRNA expression profiles of healthy individuals appear to show an abundance of microRNAs with predominant tumor suppressor activity. We hypothesize that circulating tumor suppressor microRNAs might constitute a sort of continuous tumor surveillance, whereby circulating microRNAs delivering gene expression modulating epigenetic information might halt cell transformation and tumorigenesis. This mechanism might complement the well-known cancer immune surveillance. A further hypothesis is also discussed, supposing that the tissue specific action of microRNAs might represent a putative defense mechanism against the potential tumor-promoting actions of secreted miRNA.

miR-638 is a new biomarker for outcome prediction of non-small cell lung cancer patients receiving chemotherapy

MicroRNAs (miRNAs), a class of small non-coding RNAs, mediate gene expression by either cleaving target mRNAs or inhibiting their translation. They have key roles in the tumorigenesis of several cancers, including non-small cell lung cancer (NSCLC). The aim of this study was to investigate the clinical significance of miR-638 in the evaluation of NSCLC patient prognosis in response to chemotherapy. First, we detected miR-638 expression levels in vitro in the culture supernatants of the NSCLC cell line SPC-A1 treated with cisplatin, as well as the apoptosis rates of SPC-A1. Second, serum miR-638 expression levels were detected in vivo by using nude mice xenograft models bearing SPC-A1 with and without cisplatin treatment. In the clinic, the serum miR-638 levels of 200 cases of NSCLC patients before and after chemotherapy were determined by quantitative real-time PCR, and the associations of clinicopathological features with miR-638 expression patterns after chemotherapy were analyzed. Our data helped in demonstrating that cisplatin induced apoptosis of the SPC-A1 cells in a dose- and time-dependent manner accompanied by increased miR-638 expression levels in the culture supernatants. In vivo data further revealed that cisplatin induced miR-638 upregulation in the serum derived from mice xenograft models, and in NSCLC patient sera, miR-638 expression patterns after chemotherapy significantly correlated with lymph node metastasis. Moreover, survival analyses revealed that patients who had increased miR-638 levels after chemotherapy showed significantly longer survival time than those who had decreased miR-638 levels. Our findings suggest that serum miR-638 levels are associated with the survival of NSCLC patients and may be considered a potential independent predictor for NSCLC prognosis.