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

S-Adenosylmethionine: A Multifaceted Regulator in Cancer Pathogenesis and Therapy

S-adenosylmethionine (SAMe) is a key methyl donor that plays a critical role in a variety of cellular processes, such as DNA, RNA and protein methylation, essential for maintaining genomic stability, regulating gene expression and maintaining cellular homeostasis. The involvement of SAMe in cancer pathogenesis is multifaceted, as through its multiple cellular functions, it can influence tumor initiation, progression and therapeutic resistance. In addition, the connection of SAMe with polyamine synthesis and oxidative stress management further underscores its importance in cancer biology. Recent studies have highlighted the potential of SAMe as a biomarker for cancer diagnosis and prognosis. Furthermore, the therapeutic implications of SAMe are promising, with evidence suggesting that SAMe supplementation or modulation could improve the efficacy of existing cancer treatments by restoring proper methylation patterns and mitigating oxidative damage and protect against damage induced by chemotherapeutic drugs. Moreover, targeting methionine cycle enzymes to both regulate SAMe availability and SAMe-independent regulatory effects, particularly in methionine-dependent cancers such as colorectal and lung cancer, presents a promising therapeutic approach. Additionally, exploring epitranscriptomic regulations, such as m6A modifications, and their interaction with non-coding RNAs could enhance our understanding of tumor progression and resistance mechanisms. Precision medicine approaches integrating patient subtyping and combination therapies with chemotherapeutics, such as decitabine or doxorubicin, together with SAMe, can enhance chemosensitivity and modulate epigenomics, showing promising results that may improve treatment outcomes. This review comprehensively examines the various roles of SAMe in cancer pathogenesis, its potential as a diagnostic and prognostic marker, and its emerging therapeutic applications. While SAMe modulation holds significant promise, challenges such as bioavailability, patient stratification and context-dependent effects must be addressed before clinical implementation. In addition, better validation of the obtained results into specific cancer animal models would also help to bridge the gap between research and clinical practice.

Critical role of apoptosis in MeCP2-mediated epithelial-mesenchymal transition of ARPE-19 cells

Proliferative vitreoretinopathy (PVR) is a complex disease that significantly contributes to recurrent retinal detachment. Its development is notably affected by epithelial-mesenchymal transition (EMT), where apoptosis plays a crucial role as a regulator of EMT. However, the function of MeCP2 in governing apoptosis and EMT in retinal pigment epithelial (RPE) cells and its implications for PVR development have remained inadequately understood. Thus, we investigated the impact of MeCP2 on proliferation, migration, apoptosis and EMT in ARPE-19 cells to provide a fresh perspective on the etiology of PVR. The morphological changes in ARPE-19 cells induced by recombinant human MeCP2 protein and MeCP2 knockdown were observed. Wound healing assay were performed to verify the effects of recombinant human MeCP2 protein and MeCP2 knockdown on ARPE-19 cell migration. Furthermore, cell proliferation was assessed using the CCK-8 assay and flow cytometry. Western blot analysis, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and immunofluorescence analysis were conducted to measure the protein levels associated with apoptosis, cell cycle and EMT. Western blot analysis and immunofluorescence assays confirmed that MeCP2 promoted EMT formation in ARPE-19 cells. The CCK-8 assay revealed that MeCP2 treatment enhanced the proliferation of ARPE-19 cells, whereas MeCP2 knockdown inhibited ARPE-19 cell proliferation. Treatment with recombinant human MeCP2 protein and MeCP2 knockdown altered the morphology of ARPE-19 cells. Wound healing assay demonstrated that MeCP2 knockdown inhibited ARPE-19 cell migration, and MeCP2 treatment promoted ARPE-19 cell migration. MeCP2 knockdown induced a G0/G1 phase block, inhibiting cell growth, and qRT-PCR data indicated reduced expression of cell cycle-related genes. Increased apoptosis was observed after MeCP2 knockdown in ARPE-19 cells. Overall, MeCP2 treatment stimulates cell proliferation, migration and EMT formation; conversely, MeCP2 knockdown inhibits EMT, cell proliferation, migration and cell cycle G1/S phase transition, and induces apoptosis.

Forniceal deep brain stimulation in a mouse model of Rett syndrome increases neurogenesis and hippocampal memory beyond the treatment period

BACKGROUND

Rett syndrome (RTT), caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2), severely impairs learning and memory. We previously showed that forniceal deep brain stimulation (DBS) stimulates hippocampal neurogenesis with concomitant improvements in hippocampal-dependent learning and memory in a mouse model of RTT.

OBJECTIVES

To determine the duration of DBS benefits; characterize DBS effects on hippocampal neurogenesis; and determine whether DBS influences MECP2 genotype and survival of newborn dentate granular cells (DGCs) in RTT mice.

METHODS

Chronic DBS was delivered through an electrode implanted in the fimbria-fornix. We tested separate cohorts of mice in contextual and cued fear memory at different time points after DBS. We then examined neurogenesis, DGC apoptosis, and the expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) after DBS by immunohistochemistry.

RESULTS

After two weeks of forniceal DBS, memory improvements lasted between 6 and 9 weeks. Repeating DBS every 6 weeks was sufficient to maintain the improvement. Forniceal DBS stimulated the birth of more MeCP2-positive than MeCP2-negative DGCs and had no effect on DGC survival. It also increased the expression of BDNF but not VEGF in the RTT mouse dentate gyrus.

CONCLUSION

Improvements in learning and memory from forniceal DBS in RTT mice extends well beyond the treatment period and can be maintained by repeated DBS. Stimulation of BDNF expression correlates with improvements in hippocampal neurogenesis and memory benefits.

CircNCOR1 regulates breast cancer radiotherapy efficacy by regulating CDK2 via hsa-miR-638 binding

BACKGROUND

Despite aggressive local and regional therapy, triple-negative breast cancer (TNBC) is characterized by an increased risk of locoregional recurrence. RNA-sequencing data has identified a large number of circRNAs in primary breast cancers, but the role of specific circRNAs in regulating the radiosensitivity of TNBC is not fully understood. This research aimed to investigate the function of circNCOR1 in the radiosensitivity of TNBC.

METHODS

CircRNA high-throughput sequencing was conducted on two breast cancer MDA-MB-231 and BT549 cell lines after 6 Gy radiation. The relationship between circNCOR1, hsa-miR-638, and CDK2 was determined by RNA immunoprecipitation (RIP), FISH and luciferase assays. The proliferation and apoptosis of breast cancer cells were measured by CCK8, flow cytometry, colony formation assays, and western blot.

RESULTS

Differential expression of circRNAs was closely related to the proliferation of breast cancer cells after irradiation. Overexpression of circNCOR1 facilitated the proliferation of MDA-MB-231 and BT549 cells and impaired the radiosensitivity of breast cancer cells. Additionally, circNCOR1 acted as a sponge for hsa-miR-638 to regulate the downstream target protein CDK2. Overexpression of hsa-miR-638 promoted apoptosis of breast cancer cells, while overexpression of CDK2 alleviated apoptosis and increased proliferation and clonogenicity. In vivo, overexpression of circNCOR1 partially reversed radiation-induced loosening of tumor structures and enhanced tumor cell proliferation.

CONCLUSION

Our results demonstrated that circNCOR1 bounds to hsa-miR-638 and targets CDK2, thereby regulating the radiosensitivity of TNBC.

The Epigenetic Reader Methyl-CpG-Binding Protein 2 (MeCP2) Is an Emerging Oncogene in Cancer Biology

Epigenetic mechanisms are gene regulatory processes that control gene expression and cellular identity. Epigenetic factors include the "writers", "readers", and "erasers" of epigenetic modifications such as DNA methylation. Accordingly, the nuclear protein Methyl-CpG-Binding Protein 2 (MeCP2) is a reader of DNA methylation with key roles in cellular identity and function. Research studies have linked altered DNA methylation, deregulation of MeCP2 levels, or MECP2 gene mutations to different types of human disease. Due to the high expression level of MeCP2 in the brain, many studies have focused on its role in neurological and neurodevelopmental disorders. However, it is becoming increasingly apparent that MeCP2 also participates in the tumorigenesis of different types of human cancer, with potential oncogenic properties. It is well documented that aberrant epigenetic regulation such as altered DNA methylation may lead to cancer and the process of tumorigenesis. However, direct involvement of MeCP2 with that of human cancer was not fully investigated until lately. In recent years, a multitude of research studies from independent groups have explored the molecular mechanisms involving MeCP2 in a vast array of human cancers that focus on the oncogenic characteristics of MeCP2. Here, we provide an overview of the proposed role of MeCP2 as an emerging oncogene in different types of human cancer.

Epi-miRNAs: Modern mediators of methylation status in human cancers

Methylation of the fundamental macromolecules, DNA/RNA, and proteins, is remarkably abundant, evolutionarily conserved, and functionally significant in cellular homeostasis and normal tissue/organism development. Disrupted methylation imprinting is strongly linked to loss of the physiological equilibrium and numerous human pathologies, and most importantly to carcinogenesis, tumor heterogeneity, and cancer progression. Mounting recent evidence has documented the active implication of miRNAs in the orchestration of the multicomponent cellular methylation machineries and the deregulation of methylation profile in the epigenetic, epitranscriptomic, and epiproteomic levels during cancer onset and progression. The elucidation of such regulatory networks between the miRNome and the cellular methylation machineries has led to the emergence of a novel subclass of miRNAs, namely "epi-miRNAs" or "epi-miRs." Herein, we have summarized the existing knowledge on the functional role of epi-miRs in the methylation dynamic landscape of human cancers and their clinical utility in modern cancer diagnostics and tailored therapeutics. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Methyl-CpG Binding Protein 2 as a Potential Diagnostic and Prognostic Marker Facilitates Glioma Progression Through Activation of Wnt/β-Catenin Pathway

BACKGROUND

Glioma is the primary malignant tumor in the central nervous system and has high malignancy, mortality, and recurrence rates. Because of its heterogeneity and drug resistance, the blood-brain barrier, and other factors, the treatment of glioma has mainly been surgical resection combined with traditional radiotherapy and chemotherapy. However, the therapeutic effect has not been satisfactory. Methyl-CpG binding protein 2 (MeCP2) is an epigenetic regulator that has been reported to regulate the initiation and progression of glioma. However, the underlying mechanism in glioma has remained unclear.

METHODS

The gene expression of MeCp2, miR-138-5p, the epithelial-mesenchymal transition, the apoptosis-related gene, and the Wnt/β-Catenin pathway-related gene and proliferation were detected by reverse transcription-quantitative polymerase chain reaction or Western blot. The cell proliferation and apoptosis of the glioma cell was assessed using the CCK-8 assay and flow cytometry assay. The relationship between miR-138-5p and MeCp2 was measured using the dual luciferase reporter assay. The effect of MeCp2 in U87 cells was examined in a xenograft tumorigenesis model in vivo.

RESULTS

In our study, we found that MeCP2 was upregulated in glioma tissues and cell lines and that MeCP2 knockdown repressed cell proliferation and epithelial-mesenchymal transition but boosted cell apoptosis in glioma. Furthermore, MeCP2 knockdown attenuated in vivo glioma growth in a mice model. Mechanistically, miR-138-5p hindered the expression of MeCP2 by target MeCP2 and then inactivated the Wnt/β-catenin signaling pathway. In addition, subsequent rescue assays disclosed that miR-138-5p repressed the glioma malignant phenotype and MeCP2 overexpression reversed the inhibitory effect of miR-138-5p upregulation. Consistently, overexpression of MeCP2 elevated glioma development. However, inhibition of the Wnt/β-catenin signaling pathway with XAV-939 rescued the facilitation effect by overexpressing miR-138-5p.

CONCLUSIONS

Our results have revealed that miR-138-5p/MeCP2/Wnt/β-catenin signaling might be a new target axis for glioma treatment strategies.

Small RNA sequencing and identification of Andrographis paniculata miRNAs with potential cross‑kingdom human gene targets

Cross-species post-transcriptional regulatory potential of plant derived small non-coding microRNAs (miRNAs) has been well documented by plenteous studies. MicroRNAs are transferred to host cells via oral ingestion wherein they play a decisive role in regulation of host genes; thus, miRNAs have evolved as the nascent bioactive molecules imparting pharmacological values to traditionally used medicinal plants. The present study aims to investigate small RNA profiling in order to uncover the potential regulatory role of miRNAs derived from Andrographis paniculata, one of the most widely used herb by tribal communities for liver disorders and document the pharmacological properties of A. paniculata miRNAs. In this study, high-throughput sequencing method was used to generate raw data, ~ 60 million sequences were generated from A. paniculata leaves. Using computational tools and bioinformatics approach, analyses of 3,480,097 clean reads resulted in identification of 3440 known and 51 putative novel miRNAs regulating 1365 and 192 human genes respectively. Remarkably, the identified plausible novel miRNAs apa-miR-5, apa-miR-1, apa-miR-26, and apa-miR-30 are projected to target significant host genes including CDK6, IKBKB, TRAF3, CHD4, MECP2, and ADIPOQ. Subsequent annotations revealed probable involvement of the target genes in various pathways for instance p38-MAPK, AKT, AMPK, NF-Kβ, ERK, WNT signalling, MYD88 dependant cascade, and pathways in cancer. Various diseases such as human papilloma virus infection, Alzheimer's, Non-alcoholic Fatty Liver, Alcoholic liver diseases, HepatoCellular Carcinoma (HCC), and numerous other cancers were predominantly found to be linked with target genes. Our findings postulate novel interpretations regarding modulation of human transcripts by A. paniculata miRNAs and exhibit the regulation of human diseases by plant-derived miRNAs. Though our study elucidates miRNAs as novel therapeutic agents, however, experimental validations for assessment of therapeutic potential of these miRNAs are still warranted.

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.

Construction of a synthetic methodology-based library and its application in identifying a GIT/PIX protein-protein interaction inhibitor

In recent years, the flourishing of synthetic methodology studies has provided concise access to numerous molecules with new chemical space. These compounds form a large library with unique scaffolds, but their application in hit discovery is not systematically evaluated. In this work, we establish a synthetic methodology-based compound library (SMBL), integrated with compounds obtained from our synthetic researches, as well as their virtual derivatives in significantly larger scale. We screen the library and identify small-molecule inhibitors to interrupt the protein-protein interaction (PPI) of GIT1/β-Pix complex, an unrevealed target involved in gastric cancer metastasis. The inhibitor 14-5-18 with a spiro[bicyclo[2.2.1]heptane-2,3'-indolin]-2'-one scaffold, considerably retards gastric cancer metastasis in vitro and in vivo. Since the PPI targets are considered undruggable as they are hard to target, the successful application illustrates the structural specificity of SMBL, demonstrating its potential to be utilized as compound source for more challenging targets.

MECP2 promotes the migration and invasion of gastric cancer cells by modulating the Notch1/c-Myc/mTOR signaling pathways by suppressing FBXW7 transcription

Methyl-CpG-binding protein 2 (MECP2), an epigenetic regulatory factor, promotes the carcinogenesis and progression of a number of cancers. However, its role in the migration and invasion of gastric cancer (GC), as well as the underlying molecular mechanisms, remain unclear. In this study, we found that MECP2 promoted the migration, invasion and metastasis of GC cells. Investigation of the molecular mechanism revealed that MECP2 repressed F-box and WD40 domain protein 7 (FBXW7) transcription in GC by binding to the methylated CpG sites in the FBXW7 promoter region. MECP2 expression was markedly negatively correlated with the FBXW7 level in GC tissues. FBXW7 expression was significantly downregulated in GC tissues and cell lines, and low FBXW7 expression was correlated with unfavorable clinicopathologic features. FBXW7 inhibited cell migration and invasion by regulating the Notch1/c-Myc/mTOR signaling pathways, and knockdown of FBXW7 reversed the effects of silencing MECP2. Moreover, MECP2 upregulated the Notch1/c-Myc/mTOR signaling pathways by inhibiting FBXW7 expression at the transcriptional level. This study demonstrates that MECP2 promotes the migration and invasion of GC cells by modulating the Notch1/c-Myc/mTOR signaling pathways via suppression of FBXW7 transcription. These findings suggest that MECP2 may be a novel effective therapeutic target in GC.

Bioinformatics analysis of prognostic value and immunological role of MeCP2 in pan-cancer

Methyl-CpG-binding protein 2(MeCP2) is an important epigenetic regulatory factor that promotes many tumor developments, such as liver cancer, breast cancer, and colorectal cancer. So far, no pan-cancer analysis has been reported. Therefore, this study aims to explore pan-cancer's prognostic value, immune infiltration pattern, and biological function. We used bioinformatics methods to analyze the expression and prognostic significance of MeCP2, and the relationship between MeCP2 and clinicopathological parameters, genetic variation, methylation, phosphorylation, immune cell infiltration, and biological function in pan-cancer from using a public database. The results showed that expression of MeCP2 was up-regulated in 8 cancers and down-regulated in 2 cancers, which was remarkably correlated with the prognosis, pathological stage, grade and subtype of cancers. The promoter methylation level of MeCP2 DNA was decreased in bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), liver hepatocellular carcinoma (LIHC), prostate adenocarcinoma (PRAD), uterine corpus endometrial carcinoma (UCEC), testicular germ cell tumors (TGCT), and stomach adenocarcinoma (STAD);decreased phosphorylation of S25, S90, S92, S241, S286, S325 and S435 was found in MeCP2, such as UCEC, lung adenocarcinoma (LUAD), ovarian serous cystadenocarcinoma (OV), colon adenocarcinoma (COAD), and kidney renal clear cell carcinoma (KIRC). Furthermore, MeCP2 expression was significantly associated with multiple immunomodulators and immune cell infiltration levels across most tumors. Therefore, our pan-cancer explored the prognostic markers and immunotherapeutic value of MeCP2 in different cancers.

MBD1/HDAC3-miR-5701-FGFR2 axis promotes the development of gastric cancer

Gastric cancer (GC) remains one of the leading causes of cancer-related deaths worldwide due to the lack of specific biomarkers for the early diagnosis and universal accepted therapy for advanced GC. Lower levels of miR-5701 were found in the GC tissue from the online sequencing data and confirmed in the GC tissues and GC cell lines. Overexpression of miR-5701 inhibited the proliferation and migration of GC cells and promoted the apoptosis of these cells. Bioinformatics analyses and luciferase assay showed that miR-5701 targeted FGFR2, which acted as an oncogene in GC. Nude mice with GC cells overexpressing miR-5701 exhibited smaller tumor sizes and less lung metastases. The miR-5701 expression was directly, transcriptionally inhibited by MBD1 together with HDAC3 by binding together to form a complex. Knocked down MBD1 or HDAC3 increased the miR-5701 expression. These results indicated the potential use of exogenously administered miR-5701 or agents that elevated endogenous miR-5701 to inhibit GC, improving the prognosis of patients with GC.

Heat Shock Procedure Affects Cell Division-Associated Genes in Gynogenetic Manipulation

Heat shock procedure is crucial for gynogenetic manipulation leading to diploidization of the maternal genomes; however, the underlying molecular mechanism especially the transcriptomic changes during this procedure has still not been unveiled yet. Here, the artificial gynogenesis of zebrafish (Danio rerio) using inactivated sperm from rare minnow (Gobiocypris rarus) was conducted. We found that artificial gynogenetic manipulation, including pseudo-fertilization and heat shock, decreased hatching rates, whereas heat shock treatment alone had medium hatching rates. The first cleavage changed the expression of genes associated with RNA transcription and protein synthesis. A co-expression network regulated by hub genes GIT1, Sepsecs, and FLNB was significantly correlated with heat shock procedure. The cyclin family and cyclin-dependent kinase-related genes were lowly expressed in embryos from gynogenetic zebrafish, and genes involved in controlling the cell cycle and genomic stability were significantly altered by the gynogenetic treatment. Our results show the effects of artificial gynogenesis on embryos and describe changes in gene expression that suggest drastic changes take place in cell division by heat shock procedure. These findings will contribute to an understanding of the molecular basis for germplasm improving, including the purifying effect and allogynogenetic biological effect by gynogenesis.

MeCP2 Increases Cisplatin Resistance in Human Gastric Cancer through the Activation of the AKT Pathway by Facilitating PDK-1 Transcription

BACKGROUND

Increasing evidence indicates that an imbalance of oncogenes is implicated in chemotherapy resistance in cancers. Methyl-CpG binding protein 2 (MeCP2), which acts as a master epigenetic regulator of various gene expressions, is involved in the carcinogenesis and progression of gastric cancer. However, whether this vital role may participates in acquired cisplatin resistance in GC remains unknown.

OBJECTIVE

This study aimed to determine whether inhibition of MeCP2 expression could sensitize DDP-resistant GC cells to DDP and to elucidate its underlying molecular mechanism.

METHODS

qRT-PCR and western blotting were used to evaluate MeCP2 expression in GC DDP-resistant GC cells. Subsequently, cell viability, colony formation, cell cycle, cell apoptosis and tumorigenicity assays were performed to explore the role of MeCP2 in vitro and in vivo. Chromatin immunoprecipitation-qPCR and luciferase reporter assays were used to identify whether 3-phosphoinositide-dependent protein kinase 1 (PDK-1) is a direct target gene of MeCP2.

RESULTS

MeCP2 was upregulated in malignant DDP-resistant cells compared to that in non-DDP-resistant GC cells or normal gastric epithelial cells. MeCP2 knockdown increased the sensitivity of DDP-resistant GC cells to DDP, resulting in reduced cell growth, G0/G1 phase arrest and increased apoptosis, wheras MeCP2 overexpression attenuated DDP sensitivity of DDP-resistant GC cells. In addition, MeCP2 knockdown enhanced DDP sensitivity in tumors in vivo. MeCP2 elevated PDK-1 expression by binding to its CpG sites in promoter regions, and inhibition of PDK-1 reversed the inductive effect of MeCP2 overexpression on DDP resistance in GC cells.

CONCLUSION

These findings indicate that silencing MeCP2 may potentiate DDP induced cell death, providing a promising therapeutic strategy for GC.

MeCP2 confers 5-fluorouracil resistance in gastric cancer via upregulating the NOX4/PKM2 pathway

Background

Increasing evidence suggests that aberrant methylation is involved in 5-fluorouracil (5-FU) resistance in gastric cancer (GC). Our previous work has identified that Methyl-CpG binding protein 2 (MeCP2) promotes GC progression by binding to the methylation sites of promoter regions of specific genes to affect the downstream signaling pathways. However, the function and molecular mechanisms of MeCP2 in GC 5-FU resistance remain unclear.

Methods

We detected the expression of MeCP2 in 5-FU-resistant GC cells and examined cell behaviors when MeCP2 was silenced. The molecular mechanisms were explored through chromatin immunoprecipitation (ChIP)-qRT-PCR, luciferase reporter assay, clinical tissue samples analysis, and in vivo tumorigenicity assay.

Results

MeCP2 was up-regulated in 5-FU-resistant GC cells. Knockdown of MeCP2 enhanced the sensitivity of the cells to 5-FU. Moreover, MeCP2 promoted NOX4 transcription in the cells by binding to the promoter of NOX4. Silencing NOX4 rescued the inductive effect of MeCP2 overexpression on 5-FU sensitivity of GC cells and reduced the expression of NOX4 and PKM2 in MeCP2 overexpressed 5-FU-resistant GC cells. In addition, our in vivo experiments demonstrated that MeCP2 knockdown enhanced 5-FU sensitivity in tumors.

Conclusion

MeCP2 confers 5-FU resistance in GC cells via upregulating the NOX4/PKM2 pathway, which may lead to a promising therapeutic strategy for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02489-y.

The novel lncRNA GPC5-AS1 stabilizes GPC5 mRNA by competitively binding with miR-93/106a to suppress gastric cancer cell proliferation

Long non-coding RNAs (lncRNAs) are of importance in the genesis and progression of gastric cancer (GC). GPC5-AS1 is a novel lncRNA associated with methyl-CpG-binding protein 2 (MeCP2), identified in our previous microarray analysis; however, the role of GPC5-AS1 in GC remains unknown. In the present study, we demonstrate that GPC5-AS1 is downregulated in GC cells and tissues, and this aberrant expression is regulated by MeCP2 through CpG site binding in the promoter region. Importantly, we also demonstrate that GPC5-AS1 overexpression suppresses cell proliferation, colony formation, and cell cycle transition; induces apoptosis in vitro; and inhibits tumorigenicity in vivo. The expression of the controversial gene GPC5 was downregulated in GC tissues, and elevated GPC5 level could inhibit GC cell growth. Mechanistically, we demonstrated that GPC5-AS1 stabilizes GPC5 mRNA by acting as a molecular sponge for miR-93 and miR-106a, thereby reducing GC tumor progression. In conclusion, our results suggest that GPC5-AS1 may play a pivotal role in GC and serve as a potential diagnostic biomarker and a powerful therapeutic target for GC.

G-Protein-Coupled Receptor Kinase-Interacting Protein 1 (GIT1) Promotes Head and Neck Squamous Cell Carcinoma Metastases via Activating the PI3K/AKT/mTOR Signal Pathway

OBJECTIVE

GIT1 is identified as a novel tumor oncogene in breast cancer. In this article, we aimed to explore the role of GIT1 in the progression of head and neck squamous cell carcinoma (HNSCC).

METHODS

GIT1 expression in HNSCC was detected by RT-qPCR, immunohistochemistry assay, and Western blot. HNSCC cell proliferation, migration, and invasion were examined by CCK-8 assay, Wound healing assay, and Transwell assay, respectively. Cell apoptosis was detected by flow cytometric analysis.

RESULTS

In our study, GIT1 was notably upregulated in HNSCC tissues and cells. Moreover, GIT1 expression level had positive corelation with pathological grade and nodal status of HNSCC. Functional experiments showed that knockdown of GIT1 restrained HNSCC proliferation, invasion, migration, and EMT and facilitated cell apoptosis. Furthermore, GIT1 knockdown was found to restrain HNSCC tumor growth and lung metastasis. Additionally, PI3K/AKT/mTOR signal pathway inhibitors suppressed the effect of GIT1 on HNSCC cell progression.

CONCLUSION

GIT1 was upregulated in HNSCC and facilitated HNSCC cell progression by inducing PI3K/AKT/mTOR signal pathway. Therefore, we suggested that GIT1 might be a potential target for HNSCC treatment.

POLR2A Promotes the Proliferation of Gastric Cancer Cells by Advancing the Overall Cell Cycle Progression

RNA polymerase II subunit A (POLR2A) is the largest subunit encoding RNA polymerase II and closely related to cancer progression. However, the biological role and underlying molecular mechanism of POLR2A in gastric cancer (GC) are still unclear. Our study demonstrated that POLR2A was highly expressed in GC tissue and promoted the proliferation of GC in vitro and in vivo. We also found that POLR2A participated in the transcriptional regulation of cyclins and cyclin-dependent kinases (CDKs) at each stage and promoted their expression, indicated POLR2A’s overall promotion of cell cycle progression. Moreover, POLR2A inhibited GC cell apoptosis and promoted GC cell migration. Our results indicate that POLR2A play an oncogene role in GC, which may be an important factor involved in the occurrence and development of GC.

GIT1 overexpression promotes epithelial-mesenchymal transition and predicts poor prognosis in hepatocellular carcinoma

Globally, hepatocellular carcinoma (HCC) is one of the most common causes of cancer-associated mortalities. It has a high rate of metastasis and recurrence, which predict a poor prognosis. G-protein-coupled receptor (GPCR)-kinase interacting protein-1 (GIT1) is a multifunctional scaffold protein that mediates the progression of various tumors. Studies have correlated GIT1 with HCC, however, these correlations have not been fully elucidated. Therefore, we aimed at evaluating the expression of GIT1 in HCC tissues and cells, and to investigate its role and potential mechanisms in HCC progression. The expression levels of GIT1 in HCC tissues and other cancers was determined by using the Oncomine and TCGA databases. Functional analysis of GIT1 in HCC was evaluated through in vitro and in vivo experiments, whereby, HCC cells were transfected with synthetically overexpressed and short hairpin RNA (shRNA) lentivirus-mediated plasmids. Kaplan-Meier and Cox regression methods were used to establish the associations between GIT1 and clinical outcomes of 158 HCC patients. GIT1 was found to be elevated in HCC tissues where it promoted the invasion, migration, and proliferation of HCC cells. Moreover, the overexpression of GIT1 prompted epithelial-mesenchymal transition (EMT) by activating extracellular regulated kinase 1/2 (ERK1/2) pathway, which was shown to be reversed by SCH772984, a specific ERK1/2 inhibitor. GIT1 was also found to be associated with malignant features of HCC, leading to a poorer prognosis. In conclusion, GIT1 promotes HCC progression by inducing EMT and may reflect the course of HCC patients.

miR-363-3p induces EMT via the Wnt/β-catenin pathway in glioma cells by targeting CELF2

In our previous study, we reported that CELF2 has a tumour‐suppressive function in glioma. Here, we performed additional experiments to elucidate better its role in cancer. The expression profile of CELF2 was analysed by the GEPIA database, and Kaplan–Meier curves were used to evaluate the overall survival rates. Four different online databases were used to predict miRNAs targeting CELF2, and the luciferase assay was performed to identify the binding site. The biological effects of miR‐363‐3p and CELF2 were also investigated in vitro using MTT, Transwell, and flow cytometry assays. Western blotting, qPCR, and TOP/FOP flash dual‐luciferase assays were performed to investigate the impact of miR‐363‐3p and CELF2 on epithelial‐to‐mesenchymal transition (EMT) and the Wnt/β‐catenin pathway. The effect of miR‐363‐3p was also tested in vivo using a xenograft mouse model. We observed an abnormal expression pattern of CELF2 in glioma cells, and higher CELF2 expression correlated with better prognosis. We identified miR‐363‐3p as an upstream regulator of CELF2 and confirmed its direct binding to the 3′‐untranslated region of CELF2. Cell function experiments showed that miR‐363‐3p affected multiple aspects of glioma cells. Suppressing miR‐363‐3p expression inhibited glioma cell proliferation and invasion, as well as promoted cell death via attenuating EMT and blocking the Wnt/β‐catenin pathway. These effects could be abolished by the downregulation of CELF2. Treatment with ASO‐miR‐363‐3p decreased tumour size and weight in nude mice. In conclusion, miR‐363‐3p induced the EMT, which resulted in increased migration and invasion and reduced apoptosis in glioma cell lines, via the Wnt/β‐catenin pathway by targeting CELF2.

Circular RNA Protein Tyrosine Kinase 2 Promotes Cell Proliferation, Migration and Suppresses Apoptosis via Activating MicroRNA-638 Mediated MEK/ERK, WNT/β-Catenin Signaling Pathways in Multiple Myeloma

Our previous study observed that circular RNA protein tyrosine kinase 2 (circ-PTK2) was upregulated and correlated with worse clinical features and unfavorable prognosis in multiple myeloma (MM) patients. Thus, this study aimed to further characterize the regulatory function of circ-PTK2 on cell malignant activities and its target microRNA-638 (miR-638) as well as downstream MEK/ERK, WNT/β-catenin signaling pathways in MM. The effect of circ-PTK2 on MM cell proliferation, apoptosis, migration, invasion and its potential target miRNAs was assessed by transfecting circ-PTK2 overexpression plasmids into U226 cells and circ-PTK2 knock-down plasmids into LP-1 cells. Furthermore, the interaction between circ-PTK2 and miR-638 mediated MEK/ERK and WNT/β-catenin signaling pathways was validated by rescue experiments. Circ-PTK2 was overexpressed in most MM cell lines compared to normal plasma cells. Overexpressing circ-PTK2 promoted proliferation and migration, inhibited apoptosis in U266 cells, but did not affect cell invasion; knocking down circ-PTK2 achieved opposite effect in LP-1 cells. Besides, circ-PTK2 reversely regulated miR-638 expression but not miR-4690, miR-6724, miR-6749 or miR-6775. The following luciferase reporter assay illustrated the direct bind of circ-PTK2 towards miR-638. In rescue experiments, overexpressing miR-638 suppressed proliferation, migration, while promoted apoptosis in both wild U266 cells and circ-PTK2-overexpressed U266 cells; meanwhile, overexpressing miR-638 also suppressed MEK/ERK and WNT/β-catenin pathways in both wild U266 cells and circ-PTK2-overexpressed U266 cells. Knocking down miR-638 achieved opposite effect in both wild LP-1 cells and circ-PTK2-knocked-down LP-1 cells. In conclusion, circ-PTK2 promotes cell proliferation, migration, suppresses cell apoptosis via miR-638 mediated MEK&ERK and WNT&β-catenin signaling pathways in MM.

Methyl CpG binding protein 2 promotes colorectal cancer metastasis by regulating N6 -methyladenosine methylation through methyltransferase-like 14

RNA N⁶‐methyladenosine (m⁶A) is an emerging regulatory mechanism for tumor progression in several types of cancer. However, the underlying regulation mechanisms of m⁶A methylation in colorectal cancer (CRC) remain unknown. Although the oncogenic function of methyl CpG binding protein 2 (MeCP2) has been reported, it is still unclear whether MeCP2 could alter RNA m⁶A methylation state. Here, we systematically identified MeCP2 as a prometastasis gene to regulate m⁶A methylation in CRC. Interestingly, MeCP2 could bind to methyltransferase‐like 14 (METTL14) to coregulate tumor suppressor Kruppel‐like factor 4 (KLF4) expression through changing m⁶A methylation modification. Furthermore, insulin‐like growth factor 2 mRNA‐binding protein 2 recognized the unique modified m⁶A methylation sites to enhance KLF4 mRNA stability. Taken together, these findings highlight the novel function of MeCP2 for regulating m⁶A methylation and reveal the underlying molecular mechanism for the interaction between MeCP2 and METTL14, which offers a better understanding of CRC progression and metastasis.

MeCP2 attenuates cardiomyocyte hypoxia/reperfusion-induced injury via regulation of the SFRP4/Wnt/β-catenin axis

Objective: Methylated CpG binding protein 2 (MeCP2) is closely associated with heart failure, but its role in I/R injury remains unclear. The purpose of this study was to explore the role and underling mechanism of MeCP2 in myocardial I/R injury.Methods: Hypoxia/reperfusion (H/R)-induced H9c2 cardiomyocytes was used to establish an in vitro I/R injury model. Oxidative stress was assessed by measuring reactive oxygen species (ROS) generation, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. Cell viability and cell cycle arrest were evaluated by the Cell Counting Kit-8 assay and cell cycle assay, respectively. Apoptosis was determined using flow cytometry analysis.Results: The expression of MeCP2 in H9c2 cells was decreased after H/R treatment. The overexpression of MeCP2 inhibited H/R-induced oxidative stress, cell cycle arrest and apoptosis of H9c2 cells. Moreover, MeCP2 inhibited the activation of secreted frizzled related protein 4 (SFRP4)/Wnt/β-catenin axis, and SFRP4 relieved the effect of MeCP2 on oxidative stress, cell cycle arrest and apoptosis in H/R-induced H9c2 cells.Conclusions: MeCP2 attenuated H/R-induced injury in H9c2 cardiomyocytes by modulating the SFRP4/Wnt/β-catenin axis, which suggested that MeCP2 might serve as a therapeutic target of patients with AMI after reperfusion.

LINC00518 Promotes Cell Proliferation by Regulating the Cell Cycle of Lung Adenocarcinoma Through miR-185-3p Targeting MECP2

Previous studies have shown that long intergenic non-protein coding RNA 00518 (LINC00518) are essential for the cell growth and metastasis of human cancer. However, the role of LINC00518 in lung adenocarcinoma (LUAD) is still unknown. This research put emphasis on the function of LINC00518 on the cell growth of LUAD. The lncRNA, miRNA and mRNA expression were measured by using qRT-PCR. Protein levels were measured by using Western blotting. CCK-8, colony formation assays and transwell assay were performed to evaluate the cell proliferation ability and invasion. Bioinformatic analysis and luciferase reporter assays were chosen to confirm the mechanism of LINC00518 in LUAD. We found that LINC00518 was highly expressed in LUAD specimens and the high-expression was negatively correlated with the overall survival rates. This finding was also proved in the LUAD cell lines. Through a series of in vitro and in vivo experiments, we proved that LICN00518 promoted the cell growth of LUAD by regulating the cell cycle. Moreover, LICN00518 upregulated the expression of MECP2 by mutagenesis of miR-185-3p. The results suggested that LICN00518 could be used as a survival indicator and potential therapeutic target for LUAD patients.

MicroRNA-665 facilitates cell proliferation and represses apoptosis through modulating Wnt5a/β-Catenin and Caspase-3 signaling pathways by targeting TRIM8 in LUSC

Background

MicroRNAs (miRNAs) are involved in the oncogenesis, development and transformation of lung squamous cell carcinoma (LUSC). miR-665 is clinically significant and acts as a pivotal function in some cancers. Nevertheless, the effects and the potential mechanisms of miR-665 in human LUSC are still unknown.

Methods

To analyse the clinical significant of miR-665 in human LUSC, quantitative real-time PCR (qRT-PCR) was use to measure miR-665 expression in LUSC specimen tissues and cell lines. Tripartite motif 8 (TRIM8) was verified a target of miR-665 by performing bioinformatic prediction and luciferase reporter assay. The expression levels of TRIM8 were examined through qRT-PCR and Western blotting in LUSC specimen tissues. CCK8 assay was fulfilled for analyzing the function in LUSC cell proliferation. Flow cytometry was used to detect cell and apoptosis. TRIM8 silencing and overexpression further verified the biological effects as those caused by miR-665.

Results

Here we reported that miR-665 expression was upregulated in LUSC specimen tissues and cell lines. High miR-665 levels were related to differentiation, tumor size and TNM stage. miR-665 mimics facilitated LUSC cell growth and cell cycle G1-S transition and repressed apoptosis. miR-665 inhibitor suppressed cell proliferation and G1-S transition and promoted apoptosis. miR-665 expression was negatively correlated with TRIM8 mRNA expression in LUSC. Luciferase reporter assay confirmed that TRIM8 was a direct target gene of miR-665. miR-665 mimics downregulated the TRIM8 levels, and miR-665 inhibitor upregulated the TRIM8 levels in LUSC cells. Particularly, silencing TRIM8 led to the similar effects of miR-665 mimics in LUSC cells. Overexpression of TRIM8 inhibited LUSC cell proliferation in vitro and in vivo. Furthermore, miR-665 promoted LUSC cell proliferation through facilitating the Wnt5a/β-catenin signaling pathway and restrained apoptosis via inhibiting Caspase-3 signaling pathway, whereas TRIM8 suppressed cell growth by repressing the Wnt5a/β-catenin signaling pathway and induced apoptosis through activating Caspase-3 signaling pathway.

Conclusions

The current study demonstrates that miR-665 facilitates LUSC cell proliferation and cell cycle transition by regulation of the Wnt5a/β-Catenin signaling pathway and represses cell apoptosis via modulation of Caspase-3 signaling pathway by directly targeting TRIM8. These findings suggest that miR-665 might be a potential new target for LUSC therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01913-z.

Overview of host miRNA properties and their association with epigenetics, long non-coding RNAs, and Xeno-infectious factors

MicroRNA-derived structures play impressive roles in various biological processes. So dysregulation of miRNAs can lead to different human diseases. Recent studies have extended our comprehension of the control of miRNA function and features. Here, we overview some remarkable miRNA properties that have potential implications for the miRNA functions, including different variants of a miRNA called isomiRs, miRNA arm selection/arm switching, and the effect of these factors on miRNA target selection. Besides, we review some aspects of miRNA interactions such as the interaction between epigenetics and miRNA (different miRNAs and their related processing enzymes are epigenetically regulated by multiple DNA methylation enzymes. moreover, DNA methylation could be controlled by diverse mechanisms related to miRNAs), direct and indirect crosstalk between miRNA and lnc (Long Non-Coding) RNAs as a further approach to conduct intercellular regulation called "competing endogenous RNA" (ceRNA) that is involved in the pathogenesis of different diseases, and the interaction of miRNA activities and some Xeno-infectious (virus/bacteria/parasite) factors, which result in modulation of the pathogenesis of infections. This review provides some related studies to a better understanding of miRNA involvement mechanisms and overcoming the complexity of related diseases that may be applicable and useful to prognostic, diagnostic, therapeutic purposes and personalized medicine in the future.

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.

Quantitative proteomics and phosphoproteomic analyses of mouse livers after tick-borne Babesia microti infection

Babesia microti is a tick-borne protozoan parasite that infects the red blood cells of mice, humans, and other mammals. The liver tissues of BALB/c mice infected with B. microti exhibit severe injury. To further investigate the molecular mechanisms underlying liver injury and liver self-repair after B. microti infection, data-independent acquisition (DIA) quantitative proteomics was used to analyse changes in the expression and phosphorylation of proteins in liver tissues of BALB/c mice during a B. microti infection period and a recovery period. The expression of FABP1 and ACBP, which are related to fatty acid transport in the liver, was downregulated after infection with B. microti, as was the expression of Acox1, Ehhadh and Acaa1a, which are crucial rate-limiting enzymes in the process of fatty acid β oxidation. The phosphorylation levels of AMP-activated protein kinase (AMPK) and Hormone-sensitive lipase (HSL) were also downregulated. In addition, the expression of PSMB9, CTSC, and other immune-related proteins was increased, reflecting an active immune regulation mechanism in the mice. The weights of mice infected with B. microti were significantly reduced, and the phosphorylation levels of IRS-1, c-Raf, mTOR, and other proteins related to growth and development were downregulated.

MiR-22, regulated by MeCP2, suppresses gastric cancer cell proliferation by inducing a deficiency in endogenous S-adenosylmethionine

This study investigated the effect of methyl-CpG-binding protein 2 (MeCP2) on miRNA transcription. Our results of miRNA chip assay and ChIP-seq showed that MeCP2 inhibited the expressions of numerous miRNAs by binding to their upstream elements, including not only the promoter but also the distal enhancer. Among the affected miRNAs, miR-22 was identified to remarkably suppress gastric cancer (GC) cell proliferation, arrest G1-S cell cycle transition, and induce cell apoptosis by targeting MeCP2, MTHFD2, and MTHFR. Understanding GC metabolism characteristics is the key to developing novel therapies that target GC metabolic pathways. Our study revealed that the metabolic profiles in GC tissues were altered. SAM (S-adenosylmethionine), a universal methyl donor for histone and DNA methylation, which is specifically involved in the epigenetic maintenance of cancer cells, was found increased. The production of SAM is promoted by the folate cycle. Knockdown of MTHFD2 and MTHFR, two key enzymes in folate metabolism and methyl donor SAM production, significantly suppressed GC cell proliferation. MiR-22 overexpression reduced the level of endogenous SAM by suppressing MTHFD2 and MTHFR, inducing P16, PTEN, and RASSF1A hypomethylation. In conclusion, our study suggests that miR-22 was inhibited by MeCP2, resulting in deficiency of endogenous SAM, and ultimately leading to tumor suppressor dysregulation.

Methyl-CpG-binding protein 2 drives the Furin/TGF-β1/Smad axis to promote epithelial-mesenchymal transition in pancreatic cancer cells

Methyl-CpG-binding protein 2 (MeCP2) has been characterized as an oncogene in several types of cancer. However, its precise role in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Hence, this study aimed to evaluate the potential role of MeCP2 in pancreatic cancer progression. We found that MeCP2 was upregulated in pancreatic cancer tissues, enhanced migration, invasion, and proliferation in pancreatic cancer cells, and promoted tumorigenesis. Further evidence revealed that MeCP2 remarkably increased the mesenchymal markers vimentin, N-cadherin, and Snail, and downregulated the expression of the epithelial markers E-cadherin and ZO-1, indicating that MeCP2 promotes epithelial–mesenchymal transition (EMT). In addition, we found that MeCP2 upregulated the expression of Furin, activated TGF-β1, and increased the levels of p-Smad2/3. Importantly, we demonstrated that MeCP2, as a coactivator, enhanced Smad3 binding to the furin promoter to improve its transcription. Therefore, MeCP2/Smads drive the expression of Furin to activate TGF-β1, and in turn, phosphorylate Smad2/3, which forms a positive-feedback axis to promote EMT in pancreatic cancer cells.

Serum-Derived Exosomes-Mediated Circular RNA ARHGAP10 Modulates the Progression of Non-Small-Cell Lung Cancer Through the miR-638/FAM83F Axis

Background: Non-small-cell lung cancer (NSCLC) is the leading cause of cancer deaths all over the world. Exosomes exert central roles in intercellular communication. Circular RNA Rho GTPase activating protein 10 (circARHGAP10) was related to the development of NSCLC. Nevertheless, it was unclear whether circARHGAP10 can be mediated by serum-derived exosomes in NSCLC. Materials and Methods: Protein expression of CD63, CD81, family with sequence similarity 83F (FAM83F), glucose transporter 1 (Glut1), and lactate dehydrogenase were evaluated through western blot analysis. The expression of circARHGAP10, miR-638, and FAM83F was examined by quantitative real-time polymerase chain reaction. Cell proliferation, migration, and invasion were evaluated through 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) or transwell assays. Glucose consumption and lactate production were analyzed with special commercial kits. The relationship between circARHGAP10 or FAM83F and miR-638 was identified by dual-luciferase reporter or RNA immunoprecipitation (RIP) assays. The role of circARHGAP10 in vivo was confirmed through xenograft assay. Results: circARHGAP10 was upregulated in NSCLC tissues, cells, and serum-derived exosomes. Serum-derived exosomes boosted the expression of circARHGAP10 in NSCLC cells. circARHGAP10 depletion repressed proliferation, migration, invasion, and glycolysis of NSCLC cells in vitro, and curbed tumor growth in vivo. Also, miR-638 acted as a target of circARHGAP10, miR-638 overexpression overturned circARHGAP10 upregulation-mediated acceleration of proliferation, migration, invasion, and glycolysis of NSCLC cells. Besides, miR-638 targeted FAM83F and FAM83F overexpression abolished miR-638 enhancement-mediated proliferation, migration, invasion, and glycolysis of NSCLC cells. Conclusions: Inhibition of serum-derived exosomes-mediated circARHGAP10 curbed NSCLC progression through the miR-638/FAM83F axis.

Fas and GIT1 signalling in the prefrontal cortex mediate behavioural sensitization to methamphetamine in mice

PURPOSE

Repeated methamphetamine (METH) administration in mice readily produces behavioural sensitization, but the underlying mechanisms remain elusive. The present research aimed to identify new targets affecting METH-induced behavioural sensitization.

METHODS

We first established a mouse model of METH-induced behavioural sensitization. To characterize the animal model, we performed behavioural tests at different stages of behavioural sensitization and simultaneously detected changes in several neurotransmitters in the prefrontal cortex (PFC). Next, we perfromed RNA sequencing (RNA-seq) to screen new targets, which were subsequently and verified by RT-PCR and western blot. Finally, we confirmed the roles of the new targets in METH-induced behavioural sensitization by injection of overexpressed lentiviruses and further detected related protein levels by western blot and histological changes by haematoxylin and eosin (HE) staining.

RESULTS

We successfully established a mouse model of METH-induced behavioural sensitization. The locomotor activities of the mice changed at different stages of sensitization, accompanied by changes in the levels of DA, 5-HT, GABA and glutamate. For RNA-seq analysis, we chose Fas as target, meanwhile, we chose GIT1 as target through literature. The detection of gene expression by RT-PCR indicated that METH-sensitized mice exhibited decreased levels of Fas, MEK1 and CREB and increased levels of Erk1/2 in the PFC. Western blot analysis revealed decreased Fas, GIT1, MEK1 and phosphorylated CREB levels and increased phosphorylated Erk1/2 levels in METH-sensitized mice. Injection of Fas and GIT1 injection showed that overexpression of Fas and GIT1 inhibited the induction of METH sensitization and reversed the changes in neurotransmitter levels and related protein levels, including MEK1, phosphorylated CREB and phosphorylated Erk1/2, in METH-sensitized mice. Overexpression of Fas and GIT1 also reduced histological lesions induced by METH.

CONCLUSION

The findings indicated that the development of behavioural sensitization to METH may be mediated by Fas and GIT1 through the MEK1-Erk1/2-CREB pathway.

Regulation of DNA methylation machinery by epi-miRNAs in human cancer: emerging new targets in cancer therapy

Disruption in DNA methylation processes can lead to alteration in gene expression and function that would ultimately result in malignant transformation. In this way, studies have shown that, in cancers, methylation-associated silencing inactivates tumor suppressor genes, as effectively as mutations. DNA methylation machinery is composed of several genes, including those with DNA methyltransferases activity, proteins that bind to methylated cytosine in the promoter region, and enzymes with demethylase activity. Based on a prominent body of evidence, DNA methylation machinery could be regulated by microRNAs (miRNAs) called epi-miRNAs. Numerous studies demonstrated that dysregulation in DNA methylation regulators like upstream epi-miRNAs is indispensable for carcinogenesis; consequently, the malignant capacity of these cells could be reversed by restoring of this regulatory system in cancer. Conceivably, recognition of these epi-miRNAs in cancer cells could not only reveal novel molecular entities in carcinogenesis, but also render promising targets for cancer therapy. In this review, at first, we have an overview of the methylation alteration in cancers, and the effect of this phenomenon in miRNAs expression and after that, we conduct an in-depth discussion about the regulation of DNA methylation regulators by epi-miRNAs in cancer cells.

A genome-wide analysis reveals the MeCP2-dependent regulation of genes in BGC-823 cells

Methyl-CpG-binding protein 2 (MeCP2) epigenetically modulates gene expression through genome-wide binding to methylated CpG dinucleotides. This study aimed to evaluate the effect of MeCP2 on the global gene expression profile of human gastric adenocarcinoma to determine the potential molecular mechanism of MeCP2. To identify the gene targets of MeCP2 in gastric cancer cells, we combined the expression microarray and chromatin immunoprecipitation approaches of MeCP2, followed by sequencing (ChIP-seq) to define the MeCP2-binding sites across the whole genome. The methylation levels of the promoters in BGC-823 cells were downloaded from the National Center for Biotechnology Information Gene Expression Omnibus database (GSM1093053). A total of 5,684 ChIP-enriched peaks were identified by comparing IP and Input, using a p-value threshold of 10^-5 in ChIP-seq. The bioinformatics analysis presented a predictive model of the genome-wide MeCP2-binding pattern, in which the MeCP2 binding site is closely related to the transcription start site region in the genome. The results of motif detection showed that the MeCP2-binding regions contained not only the core CpG motif but also the extended poly (A/T) motifs. Finally, an integrative analysis of the sequence features and DNA methylation states revealed that MeCP2's function as a multifunctional transcriptional regulator may not be directly related to the methylation status of the binding site. The first MeCP2 ChIP-seq and gene expression microarray analysis in BGC-823 cells revealed that MeCP2 plays multiple roles in the regulation of gene expression depending on the microenvironment, such as sequence characteristics and the methylation levels of binding sites.

HOXD3 was negatively regulated by YY1 recruiting HDAC1 to suppress progression of hepatocellular carcinoma cells via ITGA2 pathway

Objectives

HOXD3 is associated with progression of multiple types of cancer. This study aimed to identify the association of YY1 with HOXD3‐ITGA2 axis in the progression of hepatocellular carcinoma.

Materials and Methods

Bioinformatics assay was used to identify the effect of YY1, HOXD3 and ITGA2 expression in HCC tissues. The function of YY1 and HOXD3 in HCCs was determined by qRT‐PCR, MTT, apoptosis, Western blotting, colony formation, immunohistochemistry, and wound‐healing and transwell invasion assays. The relationship between YY1 and HOXD3 or HOXD3 and ITGA2 was explored by RNA‐Seq, ChIP‐PCR, dual luciferase reports and Pearson's assays. The interactions between YY1 and HDAC1 were determined by immunofluorescence microscopy and Co‐IP.

Results

Herein, we showed that the expression of YY1, HOXD3 and ITGA2 associated with the histologic and pathologic stages of HCC. Moreover, YY1, recruiting HDAC1, can directly target HOXD3 to regulate progression of HCCs. The relationship between YY1 and HOXD3 was unknown until uncovered by our present investigation. Furthermore, HOXD3 bound to promoter region of ITGA2 and up‐regulated the expression, thus activating the ERK1/2 signalling and inducing HCCs proliferation, metastasis and migration in the vitro and vivo.

Conclusions

Therefore, HOXD3, a target of YY1, facilitates HCC progression via activation of the ERK1/2 signalling by promoting ITGA2. This finding provides a new whole way to HCC therapy by serving YY1‐HOXD3‐ITGA2 regulatory axis as a potential therapeutic target for HCC therapy.

MicroRNA-4268 inhibits cell proliferation via AKT/JNK signalling pathways by targeting Rab6B in human gastric cancer

MicroRNAs (miRNAs) play critical roles in the tumorigenesis and progression of gastric cancer (GC). However, the biological function of miR-4268 in GC and its mechanism remain unclear. In the present study, qTR-PCR found that the expression of miR-4268 was significantly downregulated in GC tissues and cell lines. The overexpression of miR-4268 inhibited GC cell proliferation and the cell cycle G1/S phase transition, and induced cell apoptosis. In contrast, inhibition of miR-4268 promoted cell proliferation and G1-S transition, and suppressed cell apoptosis. Further analyses revealed that miR-4268 expression was negatively correlated with Rab6B expression in GC tissues. Rab6B was verified to be a direct target of miR-4268. Notably, silencing Rab6B resulted in the same biological effects in GC cells as those induced by overexpression of miR-4268. Importantly, both miR-4268 overexpression and Rab6B silence inhibited the AKT/JNK signaling pathways, which modulated cell cycle regulators (Cyclin D1 and CDK4). In contrast, inhibition of miR-4268 promoted the AKT/JNK signaling pathways. MiR-4268 overexpression also promoted the p38 MAPK signaling pathway. Taken together, miR-4268 suppresses GC cell proliferation through inhibiting the AKT/JNK signaling pathways by targeting Rab6B and induces cell apoptosis through promoting the p38 MAPK signaling pathway. Our findings indicate a tumor-suppressor role of miR-4268 in GC pathogenesis and the potential of miR-4268 in GC theropy.

MeCP2 facilitates breast cancer growth via promoting ubiquitination-mediated P53 degradation by inhibiting RPL5/RPL11 transcription

Methyl-CpG-binding protein 2 (MeCP2) facilitates the carcinogenesis and progression of several types of cancer. However, its role in breast cancer and the relevant molecular mechanism remain largely unclear. In this study, analysis of the Cancer Genome Atlas (TCGA) data that MeCP2 expression was significantly upregulated in breast cancer tissues, and high MeCP2 expression was correlated with poor overall survival. Knockdown of MeCP2 inhibited breast cancer cell proliferation and G1–S cell cycle transition and migration as well as induced cell apoptosis in vitro. Moreover, MeCP2 knockdown suppressed cancer cell growth in vivo. Investigation of the molecular mechanism showed that MeCP2 repressed RPL11 and RPL5 transcription by binding to their promoter regions. TCGA data revealed significantly lower RPL11 and RPL5 expression in breast cancer tissues; additionally, overexpression of RPL11/RPL5 significantly suppressed breast cancer cell proliferation and G1–S cell cycle transition and induced apoptosis in vitro. Furthermore, RPL11 and RPL5 suppressed ubiquitination-mediated P53 degradation through direct binding to MDM2. This study demonstrates that MeCP2 promotes breast cancer cell proliferation and inhibits apoptosis through suppressing RPL11 and RPL5 transcription by binding to their promoter regions.

Methylation‑associated silencing of miR‑638 promotes endometrial carcinoma progression by targeting MEF2C

Promoter methylation‑associated silencing of cancer‑associated microRNAs (miRNAs) is a common epigenetic mechanism during tumorigenesis in various types of human cancer. However, this has not been comprehensively examined in endometrial carcinoma (EC). In the present study, an miRNA microarray consisting of 1,347 common human miRNAs was used to select potential tumor suppressive miRNAs that were hyper‑methylated in EC. This led to the identification of miR‑638, miR‑210 and miR‑3665. The methylation status of miR‑638 was examined by bisulfite sequencing polymerase chain reaction and miR‑638 expression was measured by TaqMan miRNA assays. EC cell lines transfected with vectors overexpressing miR‑638, its target gene myocyte enhancer factor 2C (MEF2C) or both, were constructed. Dual‑luciferase reporter assays, a xenograft mouse model and rescue experiments were designed to study miR‑638 and its target gene MEF2C. The results indicated that the promoter region of miR‑638 was highly methylated and the expression of miR‑638 was significantly downregulated in cancerous tissues from 42 patients with EC who underwent surgical resection. Additionally, a low expression of miR‑638 was significantly associated with advanced Federation of Gynecology and Obstetrics stage and was demonstrated to indicate shorter disease‑free survival. Functional studies indicated that the overexpression of miR‑638 in EC cell lines inhibited in vitro tumor progression and in vivo tumorigenicity. MEF2C was verified as a direct target of miR‑638 and was demonstrated to mediate the tumor‑suppressive function of miR‑638 in EC.

MicroRNA-145 suppresses gastric cancer progression by targeting Hu-antigen R

Hu-antigen R (HuR) 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 largely unclear. In the present study, we found that HuR expression level was higher in GC tissues and cell lines than in adjacent normal tissues and normal gastric epithelial cell lines, and this elevated expression was found to have a significant association with lymph node metastasis. Moreover, silencing HuR with RNA interference inhibited cell viability and induced cell apoptosis through the apoptosis-related regulators (Bcl-2 and Bax) in GC cells. In addition, bioinformatic analysis revealed that HuR expression was inversely correlated with miR-145 expression in GC tissue samples, and HuR was identified as a direct target of miR-145 with the dual-luciferase reporter. Enforced expression of miR-145 inhibited the HuR expression at both mRNA and protein levels and induced similar biologic effects of silencing HuR in GC cells. Additionally, we also found that restoration of HuR could eliminate the effects induced by miR-145 in GC cells. Taken together, these findings demonstrate the exact role of the miR-145-HuR axis in the progression of GC and indicate a potential target for GC therapy.

MicroRNA-760 acts as a tumor suppressor in gastric cancer development via inhibiting G-protein-coupled receptor kinase interacting protein-1 transcription

BACKGROUND

Gastric cancer (GC) has become a serious threat to people's health. Accumulative evidence reveals that dysregulation of numerous microRNAs (miRNAs) has been found during malignant formation. So far, the role of microRNA-760 (miR-760) in the development of GC is largely unknown.

AIM

To measure the expression level of miR-760 in GC and investigate its role in gastric tumorigenesis.

METHODS

Real-time quantitative polymerase chain reaction and Western blot analysis were used to measure the expression of miR-760 and G-protein-coupled receptor kinase interacting protein-1 (GIT1). Cell growth was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and cell colony formation assays. Apoptosis was assessed by flow cytometric analysis. The relationship between miR-760 and GIT1 was verified by luciferase reporter assay.

RESULTS

The results showed that the expression of miR-760 was decreased in GC and associated with poor clinical outcomes in GC patients. Furthermore, miR-760 restrained cell proliferation and cell colony formation and induced apoptosis in GC cells. In addition, miR-760 directly targeted GIT1 and negatively regulated its expression in GC. GIT1 was upregulated in GC and predicted a worse prognosis in GC patients. We also found that upregulation of GIT1 weakened the inhibitory effect of miR-760 in GC.

CONCLUSION

In conclusion, miR-760 targets GIT1 to inhibit cell growth and promote apoptosis in GC cells. Our data demonstrate that miR-760 may be a potential target for the treatment of GC.

MicroRNA-1269 promotes cell proliferation via the AKT signaling pathway by targeting RASSF9 in human gastric cancer

Background

MicroRNAs (miRNAs) play key roles in tumorigenesis and progression of gastric cancer (GC). miR-1269 has been reported to be upregulated in several cancers and plays a crucial role in carcinogenesis and cancer progression. However, the biological function of miR-1269 in human GC and its mechanism remain unclear and need to be further elucidated.

Methods

The expression of miR-1269 in GC tissues and cell lines was detected by quantitative real-time PCR (qRT-PCR). Target prediction programs (TargetScanHuman 7.2 and miRBase) and a dual-luciferase reporter assay were used to confirm that Ras-association domain family 9 (RASSF9) is a target gene of miR-1269. The expression of RASSF9 was measured by qRT-PCR and Western blotting in GC tissues. MTT and cell counting assays were used to explore the effect of miR-1269 on GC cell proliferation. The cell cycle and apoptosis were measured by flow cytometry. RASSF9 knockdown and overexpression were used to further verify the function of the target gene.

Results

We found that miR-1269 expression was upregulated in human GC tissues and cell lines. The overexpression of miR-1269 promoted GC cell proliferation and cell cycle G1-S transition and suppressed apoptosis. The inhibition of miR-1269 inhibited cell growth and G1-S transition and induced apoptosis. miR-1269 expression was inversely correlated with RASSF9 expression in GC tissues. RASSF9 was verified to be a direct target of miR-1269 by using a luciferase reporter assay. The overexpression of miR-1269 decreased RASSF9 expression at both the mRNA and protein levels, and the inhibition of miR-1269 increased RASSF9 expression. Importantly, silencing RASSF9 resulted in the same biological effects in GC cells as those induced by overexpression of miR-1269. Overexpression of RASSF9 reversed the effects of miR-1269 overexpression on GC cells. Both miR-1269 overexpression and RASSF9 silencing activated the AKT signaling pathway, which modulated cell cycle regulators (Cyclin D1 and CDK2). In contrast, inhibition of miR-1269 and RASSF9 overexpression inhibited the AKT signaling pathway. Moreover, miR-1269 and RASSF9 also regulated the Bax/Bcl-2 signaling pathway.

Conclusions

Our results demonstrate that miR-1269 promotes GC cell proliferation and cell cycle G1-S transition by activating the AKT signaling pathway and inhibiting cell apoptosis via regulation of the Bax/Bcl-2 signaling pathway by targeting RASSF9. Our findings indicate an oncogenic role of miR-1269 in GC pathogenesis and the potential use of miR-1269 in GC therapy.

MicroRNA-561 Affects Proliferation and Cell Cycle Transition Through PTEN/AKT Signaling Pathway by Targeting P-REX2a in NSCLC

MicroRNAs (miRNAs) play crucial roles in tumorigenesis and tumor progression. miR-561 has been reported to be downregulated in gastric cancer and affects cancer cell proliferation and metastasis. However, the role and underlying molecular mechanism of miR-561 in human non-small cell lung cancer (NSCLC) remain unknown and need to be further elucidated. In this study, we discovered that miR-561 expression was downregulated in human NSCLC tissues and cell lines. The overexpression of miR-561 inhibited NSCLC cell proliferation and cell cycle G₁/S transition and induced apoptosis. The inhibition of miR-561 facilitated cell proliferation and G₁/S transition and suppressed apoptosis. miR-561 expression was inversely correlated with P-REX2a expression in NSCLC tissues. P-REX2a was confirmed to be a direct target of miR-561 using a luciferase reporter assay. The overexpression of miR-561 decreased P-REX2a expression, and the suppression of miR-561 increased P-REX2a expression. Particularly, P-REX2a silencing recapitulated the cellular and molecular effects observed upon miR-561 overexpression, and P-REX2a overexpression counteracted the effects of miR-561 overexpression on NSCLC cells. Moreover, both exogenous expression of miR-561 and silencing of P-REX2a resulted in suppression of the PTEN/AKT signaling pathway. Our study demonstrates that miR-561 inhibits NSCLC cell proliferation and G₁/S transition and induces apoptosis through suppression of the PTEN/AKT signaling pathway by targeting P-REX2a. These findings indicate that miR-561 plays a significant role in NSCLC progression and serves as a potential therapeutic target for NSCLC.

Diagnostic biomarker and therapeutic target applications of miR-326 in cancers: A systematic review

MicroRNAs (miRNAs) are endogenous mediators of RNA interference and have key roles in the modulation of gene expression under healthy, inflamed, stimulated, carcinogenic, or other cells, and tissues of a pathological state. Many studies have proved the association between miRNAs and cancer. The role of miR-326 as a tumor suppressor miRNA in much human cancer confirmed. We will explain the history and the role of miRNAs changes, especially miR-326 in cancers and other pathological conditions. Attuned with these facts, this review highlights recent preclinical and clinical research performed on miRNAs as novel promising diagnostic biomarkers of patients at early stages, prediction of prognosis, and monitoring of the patients in response to treatment. All related publications retrieved from the PubMed database, with keywords such as epigenetic, miRNA, microRNA, miR-326, cancer, diagnostic biomarker, and therapeutic target similar terms from 1899 to 2018 with limitations in the English language. Recently, researchers have focused on the impacts of miRNAs and their association in inflammatory, autoinflammatory, and cancerous conditions. Recent studies have suggested a major pathogenic role in cancers and autoinflammatory diseases. Investigations have explained the role of miRNAs in cancers, autoimmunity, and autoinflammatory diseases, and so on. The miRNA-326 expression has an important role in cancer conditions and other diseases.

The Expression of Transcription Factors Mecp2 and CREB Is Modulated in Inflammatory Pelvic Pain

Early activation of transcription factors is one of the epigenetic mechanisms contributing to the induction and maintenance of chronic pain states. Previous studies identified the changes in a number of nociception-related genes, such as calcitonin gene-related peptide (CGRP), substance P (SP), and brain-derived neurotropic factor (BDNF) in the pelvic organs after transient colonic inflammation. The gene and protein expression of these neuropeptides could be modulated by transcription factors Methyl-CpG-binding protein 2 (Mecp2) and cAMP response element-binding protein (CREB). In this study, we aimed to evaluate time-dependent changes in the expression levels of Mecp2 and CREB in the lumbosacral (LS) spinal cord and sensory ganglia after inflammation-induced pelvic pain in rat. Adult Sprague-Dawley rats were treated with 2,4,6-trinitrobenzenesulfonic acid (TNBS) to induce transient colonic inflammation. LS (L6-S2) spinal cord segments and respective dorsal root ganglias (DRGs) were isolated from control and experimental animals at 1, 2, 6, 24 h and 3 days post-TNBS treatment. Immunohistochemical (IHC) labeling and Western blotting experiments were performed to assess the expression of Mecp2, CREB and their phosphorylated forms. Total Mecp2 expression, but not phosphorylated p-Mecp2 (pS421Mecp2) expression was detected in the cells of the spinal dorsal horn under control conditions. Colonic inflammation triggered a significant decrease in the number of Mecp2-expressing neurons in parallel with elevated numbers of pS421Mecp2-expressing cells at 2 h and 6 h post-TNBS. The majority of Mecp2-positive cells (80 ± 6%) co-expressed CREB. TNBS treatment caused a transient up-regulation of CREB-expressing cells at 1 h post-TNBS only. The number of cells expressing phosphorylated CREB (pS133CREB) did not change at 1 h and 2 h post-TNBS, but was down-regulated by three folds at 6 h post-TNBS. Analysis of DRG sections revealed that the number of Mecp2-positive neurons was up-regulated by TNBS treatment, reaching three-fold increase at 2 h post-TNBS, and eight-fold increase at 6 h post-TNBS (p ≤ 0.05 to control). These data showed early changes in Mecp2 and CREB expression in the dorsal horn of the spinal cord and sensory ganglia after colonic inflammation, suggesting a possible contribution Mecp2 and CREB signaling in the development of visceral hyperalgesia and pelvic pain following peripheral inflammation.

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.

MiR-106a* inhibits oral squamous cell carcinoma progression by directly targeting MeCP2 and suppressing the Wnt/β-Catenin signaling pathway

MicroRNAs (miRNAs) play critical roles in the tumorigenesis and progression of oral squamous cell carcinoma (OSCC). MiR-106a* functions as a tumor suppressor miRNA in several cancers; however, its role in OSCC has not been elucidated. We investigated the role of miR-106a* in human OSCC and explored its relevant mechanisms. The expression of miR-106a* was significantly downregulated in OSCC tissues and cell lines. The overexpression of miR-106a* inhibited OSCC cell proliferation and the cell cycle G1-S transition, and induced apoptosis. In contrast, inhibition of miR-106a* promoted cell proliferation and G1-S transition and suppressed apoptosis. The expression of miR-106a* inversely correlated with methyl-CpG binding protein 2 (MeCP2) expression in OSCC tissues. Using a luciferase reporter assay, MeCP2 was determined to be a direct target of miR-106a*. Overexpression of miR-106a* decreased MeCP2 expression at both the mRNA and protein levels, while inhibition of miR-106a* increased MeCP2 expression. Importantly, overexpression of MeCP2 eliminated the effects of miR-106a* overexpression in OSCC cells and silencing of MeCP2 recapitulated the cellular and molecular effects observed with miR-106a* overexpression. MeCP2 may promote OSCC cell proliferation by activating the Wnt/β-Catenin signaling pathway. Taken together, our study demonstrated that miR-106a* inhibited OSCC cell proliferation by suppression of the Wnt/β-Catenin signaling pathway and induced apoptosis through regulation of Caspase 3/9 expression via targeting MeCP2. These findings suggest that miR-106a* acted as a tumor suppressor in the progression of OSCC and may be a potential new target for OSCC diagnosis and therapy.

Downregulation of miR-638 promotes progression of breast cancer and is associated with prognosis of breast cancer patients

Background

Breast cancer is the most common tumor among women. miR-638 has been demonstrated to play an important role in various cancers.

Purpose

In this study, we aimed to investigate the function and prognostic value of miR-638 in breast cancer.

Methods

Quantitative real-time polymerase chain reaction analysis was used to evaluate the expression of miR-638 in breast cancer tissues and cell lines. The correlation of miR-638 with clinicopathological features was analyzed using the chi-squared test. Kaplan–Meier survival analysis and Cox regression assay were performed to investigate the prognostic value of miR-638 in breast cancer patients. The effects of miR-638 on the biological behavior of breast cancer cells were evaluated using functional assays.

Results

The expression of miR-638 was downregulated in breast cancer tissues and cell lines (all P<0.05). Decreased expression of miR-638 was significantly correlated with lymph node metastasis (P=0.015) and TNM stage (P=0.021). Patients with low miR-638 expression had shorter overall survival compared with those with high levels (Log-rank P=0.025). The miR-638 could be considered as an independent prognostic factor for the patients (HR =0.321, 95% CI =0.117–0.882, P=0.027). Downregulation of miR-638 was capable of promoting cell proliferation, migration, and invasion in MDA-MB-231 and MCF-7 cells.

Conclusion

All the results indicate that miR-638 is a tumor suppressor in breast cancer and is involved in the progression of breast cancer. Thus, it may serve as a prognostic biomarker for breast cancer.

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.