Epigenetic silencing of methyl-CpG-binding protein 2 gene affects proliferation, invasion, migration, and apoptosis of human osteosarcoma cells

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.

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.

Increased DEF6 expression is correlated with metastasis and poor prognosis in human osteosarcoma

Metastasis is the primary cause of high mortality in patients with osteosarcoma (OS). However, the molecular mechanisms underlying the regulation of metastatic disease are yet to be determined. Differentially expressed in FDCP 6 homolog (DEF6) has been demonstrated to be correlated with the metastatic behavior of several cancers, such as breast, ovarian and colorectal cancers. However, the role of DEF6 in OS remains unknown. Accordingly, the current study aimed to investigate the relationship between DEF6 expression and the malignant behavior of OS. The results revealed that high levels of DEF6 in OS tissues were associated with advanced clinical stage and metastases. Furthermore, immunohistochemistry results predicted a poor prognosis in 58 human OS specimens. Additionally, DEF6 expression was reported to be upregulated in human OS cell lines compared with a normal osteoblast cell line. small interfering RNA transfection, cell proliferation and colony formation assays, wound healing assays and Transwell assays were performed. DEF6 was not identified to be a major driver of OS cell proliferation, but it significantly contributed to metastatic potential in vitro. In addition, bioinformatics, western blotting and immunohistochemistry results indicated that MMP9 expression was positively correlated with DEF6 expression in human OS. To summarize, the results revealed that increased levels of DEF6 were associated with metastasis and poor prognosis in human OS and that DEF6 expression is positively correlated with MMP9 expression. The results indicated that DEF6 may serve as a potential antimetastatic target for OS.

MeCP2 inhibits proliferation and migration of breast cancer via suppression of epithelial-mesenchymal transition

Methyl‐CpG‐binding protein 2 (MeCP2) is an important epigenetic regulator for normal neuronal maturation and brain glial cell function. Additionally, MeCP2 is also involved in a variety of cancers, such as breast, prostate, lung, liver and colorectal. However, whether MeCP2 contributes to the progression of breast cancer remains unknown. In the present study, we investigated the role of MeCP2 in cell proliferation, migration and invasion in vitro. We found that knockdown of MeCP2 inhibited expression of epithelial‐mesenchymal transition (EMT)‐related markers in breast cancer cell lines. In conclusion, our study suggests that MeCP2 inhibits proliferation and invasion through suppression of the EMT pathway in breast cancer.

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.

TSSC3 promotes autophagy via inactivating the Src-mediated PI3K/Akt/mTOR pathway to suppress tumorigenesis and metastasis in osteosarcoma, and predicts a favorable prognosis

BACKGROUND

Over the last two or three decades, the pace of development of treatments for osteosarcoma tends has been slow. Novel effective therapies for osteosarcoma are still lacking. Previously, we reported that tumor-suppressing STF cDNA 3 (TSSC3) functions as an imprinted tumor suppressor gene in osteosarcoma; however, the underlying mechanism by which TSSC3 suppresses the tumorigenesis and metastasis remain unclear.

METHODS

We investigated the dynamic expression patterns of TSSC3 and autophagy-related proteins (autophagy related 5 (ATG5) and P62) in 33 human benign bone tumors and 58 osteosarcoma tissues using immunohistochemistry. We further investigated the correlations between TSSC3 and autophagy in osteosarcoma using western blotting and transmission electronic microscopy. CCK-8, Edu, and clone formation assays; wound healing and Transwell assays; PCR; immunohistochemistry; immunofluorescence; and western blotting were used to investigated the responses in TSSC3-overexpressing osteosarcoma cell lines, and in xenografts and metastasis in vivo models, with or without autophagy deficiency caused by chloroquine or ATG5 silencing.

RESULTS

We found that ATG5 expression correlated positively with TSSC3 expression in human osteosarcoma tissues. We demonstrated that TSSC3 was an independent prognostic marker for overall survival in osteosarcoma, and positive ATG5 expression associated with positive TSSC3 expression suggested a favorable prognosis for patients. Then, we showed that TSSC3 overexpression enhanced autophagy via inactivating the Src-mediated PI3K/Akt/mTOR pathway in osteosarcoma. Further results suggested autophagy contributed to TSSC3-induced suppression of tumorigenesis and metastasis in osteosarcoma in vitro and in vivo models.

CONCLUSIONS

Our findings highlighted, for the first time, the importance of autophagy as an underlying mechanism in TSSC3-induced antitumor effects in osteosarcoma. We also revealed that TSSC3-associated positive ATG5 expression might be a potential predictor of favorable prognosis in patients with osteosarcoma.

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.

TSSC3 represses self-renewal of osteosarcoma stem cells and Nanog expression by inhibiting the Src/Akt pathway

Osteosarcoma is the most common type of bone cancer, and the second leading cause of cancer-related death in children and young adults. Osteosarcoma stem cells are essential for osteosarcoma initiation, metastasis, chemoresistance and recurrence. In the present study, we report that: 1) higher TSSC3 expression indicates a better prognosis for osteosarcoma patients, and; 2) overexpression of TSSC3 significantly decreases sphere-forming capacity, tumor initiation, stemness-related surface markers and Nanog expression in osteosarcoma cells. We also discovered that higher Nanog expression correlates to a worse prognosis for osteosarcoma patients, and overexpression of Nanog increases the stem-related phenotype in osteosarcoma cells. Knockdown of Nanog suppresses these phenotypes. Inhibition of Nanog expression and self-renewal of osteosarcoma cells by TSSC3 overexpression appears to be mediated through inactivation of the Src/Akt pathway. In the clinical setting, expression of TSSC3, p-Src and Nanog is associated with recurrence, metastasis and surgical intervention. Lower TSSC3 expression, higher Nanog expression or higher p-Src expression indicate a poor prognosis for osteosarcoma patients. Overall, our study demonstrates that TSSC3 inhibits the stem-like phenotype and Nanog expression by inactivation of the Src/Akt pathway; this emphasizes the importance of Nanog in osteosarcoma stem cells.

MECP2 expression in gastric cancer and its correlation with clinical pathological parameters

This study is to investigate the expression of methyl CpG binding protein 2 (MECP2) in gastric cancer (GC) and its clinical significance.Expression of MECP2 was analyzed in 69 cases of GC tissues and 12 paracancerous tissues, either by qRT-PCR at the mRNA level or by Western blot and immunochemistry at the protein level. The correlation of MECP2 expression with clinicopathological parameters was analyzed in the 69 GC patients, and validated in data from the TCGA database. The effect of MECP2 expression on survival was also investigated.MECP2 was significantly increased at both mRNA and protein levels in GC compared with paracancerous tissues. MECP2 positive expression was significantly correlated with the TNM stages, histological types, and lymph node metastasis status, but was not correlated with sex or age. Significantly shorter overall survival and disease-free survival was observed in MECP2 positive GC cases compared with the MECP2 negative cases. Univariate and multivariate analyses showed that gender, histological type, lymph node metastasis, and MECP2 expression were independent prognostic factors of GC.The dysregulated expression of MECP2 in GC and its correlation to clinicopathological parameters indicate that MECP2 may regulate the development of GC.

MeCP2 Promotes Gastric Cancer Progression Through Regulating FOXF1/Wnt5a/β-Catenin and MYOD1/Caspase-3 Signaling Pathways

Methyl-CpG binding protein 2 (MeCP2) has recently been characterized as an oncogene frequently amplified in several types of cancer. However, its precise role in gastric cancer (GC) and the molecular mechanism of MeCP2 regulation are still largely unknown. Here we report that MeCP2 is highly expressed in primary GC tissues and the expression level is correlated with the clinicopathologic features of GC. In our experiments, knockdown of MeCP2 inhibited tumor growth. Molecular mechanism of MeCP2 regulation was investigated using an integrated approach with combination of microarray analysis and chromatin immunoprecipitation sequencing (ChIP-Seq). The results suggest that MeCP2 binds to the methylated CpG islands of FOXF1 and MYOD1 promoters and inhibits their expression at the transcription level. Furthermore, we show that MeCP2 promotes GC cell proliferation via FOXF1-mediated Wnt5a/β-Catenin signaling pathway and suppresses apoptosis through MYOD1-mediated Caspase-3 signaling pathway. Due to its high expression level in GC and its critical function in driving GC progression, MeCP2 represents a promising therapeutic target for GC treatment.

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MeCP2 inhibits FOXF1 and MYOD1 transcription by binding to their promoter regions.

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MeCP2 promotes GC cell proliferation via FOXF1-mediated Wnt/β-Catenin signaling pathway.

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MeCP2 suppresses GC cell apoptosis through MYOD1-mediated Caspase-3 signaling pathway.

Gastric cancer is the fourth most common malignant cancer and the third most frequent cause of cancer-related deaths worldwide. The molecular mechanism underlying gastric carcinogenesis and progression is still unknown. Methyl-CpG binding protein 2 (MeCP2) has recently been characterized as an oncogene frequently amplified in several types of cancer. However, its precise role and the molecular mechanism of MeCP2 regulation in gastric cancer are largely unknown. Our results show that MeCP2 promotes gastric cancer cell proliferation via FOXF1-mediated Wnt5a/β-Catenin signaling pathway and suppresses cell apoptosis through MYOD1-mediated Caspase-3 signaling pathway. MeCP2 represents a promising therapeutic target for gastric cancer treatment.

RanBP9/TSSC3 complex cooperates to suppress anoikis resistance and metastasis via inhibiting Src-mediated Akt signaling in osteosarcoma

Suppression of anoikis is a prerequisite for tumor cell metastasis, which is correlated with chemoresistance and poor prognosis. We characterized a novel interaction between RanBP9 SPRY domain and TSSC3 PH domain by which RanBP9/TSSC3 complex exerts transcription and post-translation regulation in osteosarcoma. RanBP9/TSSC3 complex was inversely correlated with a highly anoikis-resistant phenotype in osteosarcoma cells and metastasis in human osteosarcoma. RanBP9 cooperated with TSSC3 to inhibit anchorage-independent growth and to promote anoikis in vitro and suppress lung metastasis in vivo. Moreover, RanBP9 SPRY domain was required for RanBP9/TSSC3 complex-mediated anoikis resistance. Mechanistically, RanBP9 formed a ternary complex with TSSC3 and Src to scaffold this interaction, which suppressed both Src and Src-dependent Akt pathway activations and facilitated mitochondrial-associated anoikis. Collectively, the newly identified RanBP9/TSSC3 complex cooperatively suppress metastasis via downregulation of Src-dependent Akt pathway to expedite mitochondrial-associated anoikis. This study provides a biological basis for exploring the therapeutic significance of dual targeting of RanBP9 and TSSC3 in osteosarcoma.

Epigenetic factors MeCP2 and HDAC6 control α-tubulin acetylation in cardiac fibroblast proliferation and fibrosis

AIM AND OBJECTIVE

Cardiac fibrosis is an important pathological feature of cardiac remodeling in heart diseases. Methyl-CpG-binding protein 2 (MeCP2) is a transcription inhibitor, and plays a key role in the fibrotic diseases. However, the precise role of MeCP2 in cardiac fibrosis remains unclear. α-tubulin plays an essential role in cell function, whereby the acetylation state of α-Tubulin dictates the efficiency of cell proliferation and differentiation. This study was undertaken to investigate that MeCP2 dynamics affect the acetylation state of α-tubulin in the cardiac fibrosis.

METHODS

Forty adult male Sprague-Dawley (SD) rats were randomly divided into two groups, cardiac fibrosis was produced by common ISO. Cardiac fibroblasts (CFs) were harvested from SD neonate rats and cultured. The expression of HDAC6, MeCP2, α-SMA, collagen I was measured by western blotting and qRT-PCR. siRNA of HDAC6 and MeCP2 effect the proliferation of cardiac fibroblasts, and affect the acetylation state of α-tubulin.

RESULTS

We have found the acetylation state of α-tubulin in cardiac fibroblasts as well as cardiac tissue from a ISO-induced rat cardiac fibrosis model and observed a reduction in acetylated α-tubulin and an increase in the α-tubulin-specific deacetylase, histone deacetylase 6 (HDAC6). Furthermore, we have shown that treatment of cardiac fibroblasts with HDAC6 inhibitor Tubastatin A and HDAC6-siRNA can restore α-tubulin acetylation levels. In addition, treatment of cardiac fibroblasts with MeCP2-siRNA blocked cell proliferation. Knockdown of MeCP2 suppresses HDAC6 expression in activated cardiac fibroblasts but increases the acetylation of α-tubulin.

CONCLUSIONS

We demonstrated that MeCP2 may negatively control the acetylation of α-tubulin through HDAC6 in cardiac fibroblast proliferation and fibrosis. This study indicated that MeCP2 could be a potentially new therapeutic option for cardiac fibrosis.

Downregulation of tumor suppressing STF cDNA 3 promotes epithelial-mesenchymal transition and tumor metastasis of osteosarcoma by the Wnt/GSK-3β/β-catenin/Snail signaling pathway

Epithelial to mesenchymal transition (EMT) has received considerable attention as a conceptual paradigm for explaining the invasive and metastatic behavior of cells during cancer progression. Our previous study showed that loss of expression of TSSC3 is positively associated with osteosarcoma malignancy and progression. However, whether TSSC3 mediates EMT in osteosarcoma is poorly understood. In the present study, we determined that TSSC3 downregulation induced cell migration and invasion ability and promoted mesenchymal transition of osteosarcoma cells by upregulating mesenchymal markers and inhibiting the epithelial markers. Furthermore, TSSC3 downregulation elicited a signaling cascade that included increased levels of Wnt3a and LRP5, inactivation of GSK-3β, accumulation of nuclear β-catenin and Snail, the augmented binding of β-catenin to TCF-4, and accordingly increased the expression of Wnt target genes (CD44, MMP7). The gene knockdown of these signaling proteins could inhibit TSSC3 downregulation-promoted EMT, migration, and invasion in osteosarcoma. Finally, TSSC3 overexpression obviously inhibited cell migration, invasion, and repressed mesenchymal phenotypes, reducing lung metastasis through GSK-3β activation. Collectively, TSSC3 downregulation promotes the EMT of osteosarcoma cells by regulating EMT markers via a signal transduction pathway that involves Snail, Wnt-β-catenin/TCF, and GSK-3β.

The mesmiRizing complexity of microRNAs for striated muscle tissue engineering

microRNAs (miRs) are small non-protein-coding RNAs, able to post-transcriptionally regulate many genes and exert pleiotropic effects. Alteration of miR levels in tissues and in the circulation has been associated with various pathological and regenerative conditions. In this regard, tissue engineering of cardiac and skeletal muscles is a fascinating context for harnessing the complexity of miR-based circuitries and signals. In this review, we will focus on miR-driven regulation of cardiac and skeletal myogenic routes in homeostatic and challenging states. Furthermore, we will survey the intriguing perspective of exosomal and circulating miRs as novel paracrine players, potentially useful for current and future approaches of regenerative medicine for the striated muscles.

Transcriptomic Analysis of mRNAs in Human Monocytic Cells Expressing the HIV-1 Nef Protein and Their Exosomes

The Nef protein of human immunodeficiency virus (HIV) promotes viral replication and progression to AIDS. Besides its well-studied effects on intracellular signaling, Nef also functions through its secretion in exosomes, which are nanovesicles containing proteins, microRNAs, and mRNAs and are important for intercellular communication. Nef expression enhances exosome secretion and these exosomes can enter uninfected CD4 T cells leading to apoptotic death. We have recently reported the first miRNome analysis of exosomes secreted from Nef-expressing U937monocytic cells. Here we show genome-wide transcriptome analysis of Nef-expressing U937 cells and their exosomes. We identified four key mRNAs preferentially retained in Nef-expressing cells; these code for MECP2, HMOX1, AARSD1, and ATF2 and are important for chromatin modification and gene expression. Interestingly, their target miRNAs are exported out in exosomes. We also identified three key mRNAs selectively secreted in exosomes from Nef-expressing U937 cells and their corresponding miRNAs being preferentially retained in cells. These are AATK, SLC27A1, and CDKAL and are important in apoptosis and fatty acid transport. Thus, our study identifies selectively expressed mRNAs in Nef-expressing U937 cells and their exosomes and supports a new mode on intercellular regulation by the HIV-1 Nef protein.