Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling

miR-29a-3p promotes migration and invasion in ameloblastoma via Wnt/β-catenin signaling by targeting catenin beta interacting protein 1

BACKGROUND

Ameloblastoma (AB) is a common epithelial odontogenic tumor. The Wnt/β-catenin pathway has been found to be related to AB invasion.

METHODS

The alteration expression of microRNAs (miRNAs) and messenger RNAs (mRNAs) was performed by miRNA and mRNA microarray analysis and validated by quantitative real-time polymerase chain reaction (RT-PCR). The effects of miR-29a-3p on migration and invasion in AB cells were evaluated by a transwell assay. Bioinformatic prediction was conducted using the miRSystem and validated by quantitative RT-PCR, western blot, and a luciferase reporter assay.

RESULTS

miR-29a-3p was overexpressed in AB tissues, which promoted the migration and invasion of AB cells in vitro. Catenin beta interacting protein 1 (CTNNBIP1), a negative regulator of the Wnt/β-catenin pathway, was predicted to be a target of miR-29a-3p. miR-29a-3p inhibited the expression of CTNNBIP1 and promoted the expression of the downstream molecules of the Wnt/β-catenin pathway.

CONCLUSIONS

miR-29a-3p promoted migration and invasion in AB via Wnt/β-catenin signaling by targeting CTNNBIP1.

Epigenetic modification of miR-663 controls mitochondria-to-nucleus retrograde signaling and tumor progression

The normal cellular function requires communication between mitochondria and the nucleus, termed mitochondria-to-nucleus retrograde signaling. Disruption of this mechanism has been implicated in the development of cancers. Many proteins are known modulators of retrograde signaling, but whether microRNAs (miRNAs) are also involved is unknown. We conducted an miRNA microarray analysis using RNA from a parental cell line, a Rho⁰ line lacking mitochondrial DNA (mtDNA) and a Rho⁰ line with restored mtDNA. We found that miR-663 was down-regulated in the mtDNA-depleted Rho⁰ line. mtDNA restoration reversed this miRNA to parental level, suggesting that miR-663 may be epigenetically regulated by retrograde signaling. By using methylation-specific PCR and bisulfite sequencing we demonstrate that miR-663 promoter is epigenetically regulated not only by genetic but also by pharmacological disruption of oxidative phosphorylation (OXPHOS). Restoration of OXPHOS Complex I inhibitor-induced miR-663 expression by N-acetylcysteine suggested that reactive oxygen species (ROS) play a key role in epigenetic regulation of miR-663. We determined that miR-663 regulates the expression of nuclear-encoded respiratory chain subunits involved in Complexes I, II, III, and IV. miR-663 also controlled the expression of the Complexes I (NDUFAF1), II (SDHAF2), III (UQCC2), and IV (SCO1) assembly factors and was required for stability of respiratory supercomplexes. Furthermore, using luciferase assays, we found that miR-663 directly regulates UQCC2. The anti-miR-663 reduced OXPHOS complex activity and increased in vitro cellular proliferation and promoted tumor development in vivo in mice. We also found that increased miR-663 expression in breast tumors consistently correlates with increased patient survival. We provide the first evidence for miRNA controlling retrograde signaling, demonstrating its epigenetic regulation and its role in breast tumorigenesis.

MicroRNA-135b inhibits odontoblast-like differentiation of human dental pulp cells by regulating Smad5 and Smad4

AIM

To investigate the function of miRNAs in odontoblast-like differentiation of human dental pulp cells (hDPCs).

METHODOLOGY

Integrated comparative miRNA microarray profiling was used to determine the differential miRNAs expression in odontoblast-like differentiation of hDPCs. The abundance of microRNA-135b (miR-135b) was measured by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). Bioinformatic analyses combined with luciferase assays were utilized to identify the targets interacting with miR-135b. Overexpression of miR-135b was performed to investigate the role and mechanism in odontoblast-like differentiation of hDPCs. Statistical analysis was performed by one-way analysis of variance (anova) or Student's t-test.

RESULTS

Thirty-six differentially expressed microRNAs in odontoblast-like differentiation of hDPCs were identified. MiR-135b expression was significantly downregulated during hDPCs differentiation (P < 0.05). In addition, miR-135b was able to bind to the 3'-UTR of the Smad5 and Smad4 and repressed these two genes expression (P < 0.05). Furthermore, overexpression of miR-135b suppressed odontoblast-like differentiation of hDPCs and attenuated the expression of Smad5 and Smad4 (P < 0.05).

CONCLUSIONS

These observations indicated a potential role of miR-135b in mediating odontoblast-like differentiation of hDPCs and inhibition of miR-135b might be a promising therapeutic way to facilitate dentine tissue engineering.

MicroRNA-3646 Contributes to Docetaxel Resistance in Human Breast Cancer Cells by GSK-3β/β-Catenin Signaling Pathway

Acquisition of resistance to docetaxel (Doc) is one of the most important problems in treatment of breast cancer patients, but the underlying mechanisms are still not fully understood. In present study, Doc-resistant MDA-MB-231 and MCF-7 breast cancer cell lines (MDA-MB-231/Doc and MCF-7/Doc) were successfully established in vitro by gradually increasing Doc concentration on the basis of parental MDA-MB-231 and MCF-7 cell lines (MDA-MB-231/S and MCF-7/S). The potential miRNAs relevant to the Doc resistance were screened by miRNA microarray. We selected 5 upregulated miRNAs (has-miR-3646, has-miR-3658, has-miR-4438, has-miR-1246, and has-miR-574-3p) from the results of microarray for RT-qPCR validation. The results showed that expression level of miR-3646 in MDA-MB-231/Doc cells was significantly higher than in MDA-MB-231/S cells. Compared to MCF-7/S cells, miR-3646 expression was up-regulated in MCF-7/Doc cells. Further studies revealed that transfection of miR-3646 mimics into MDA-MB-231/S or MCF-7/S cells remarkably increased their drug resistance, in contrast, transfection of miR-3646 inhibitors into MDA-MB-231/Doc or MCF-7/Doc cells resulted in significant reduction of the drug resistance. By the pathway enrichment analyses for miR-3646, we found that GSK-3β/β-catenin signaling pathway was a significant pathway, in which GSK-3β was an essential member. RT-qPCR and Western blot results demonstrated that miR-3646 could regulate GSK-3β mRNA and protein expressions. Furthermore, a marked increase of both nuclear and cytoplasmic β-catenin expressions (with phosphorylated-β-catenin decrease) was observed in MDA-MB-231/Doc cells compared with MDA-MB-231/S cells, and their expression were positively related to miR-3646 and negatively correlated with GSK-3β. Taken together, our results suggest that miR-3646-mediated Doc resistance of breast cancer cells maybe, at least in part, through suppressing expression of GSK-3β and resultantly activating GSK-3β/β-catenin signaling pathway.

MicroRNA Regulation of Human Breast Cancer Stem Cells

MicroRNAs (miRNAs) are involved in virtually all biological processes, including stem cell maintenance, differentiation, and development. The dysregulation of miRNAs is associated with many human diseases including cancer. We have identified a set of miRNAs differentially expressed between human breast cancer stem cells (CSCs) and non-tumorigenic cancer cells. In addition, these miRNAs are similarly upregulated or downregulated in normal mammary stem/progenitor cells. In this review, we mainly describe the miRNAs that are dysregulated in human breast CSCs directly isolated from clinical specimens. The miRNAs and their clusters, such as the miR-200 clusters, miR-183 cluster, miR-221-222 cluster, let-7, miR-142 and miR-214, target the genes and pathways important for stem cell maintenance, such as the self-renewal gene BMI1, apoptosis, Wnt signaling, Notch signaling, and epithelial-to-mesenchymal transition. In addition, the current evidence shows that metastatic breast CSCs acquire a phenotype that is different from the CSCs in a primary site. Thus, clarifying the miRNA regulation of the metastatic breast CSCs will further advance our understanding of the roles of human breast CSCs in tumor progression.

β catenin in health: A review

β catenin belongs to the armadillo family of proteins. It plays a crucial role in developmental and homeostatic processes. Wnts are a family of 19 secreted glycoproteins that transduce multiple signaling cascades, including the canonical Wnt/β catenin pathway, Wnt/Ca(2+) pathway and the Wnt/polarity pathway. This is a review on β catenin, Wnt proteins and their secretion, the signaling pathway, the associated factors and the crucial role of β catenin in odontogenesis.

Regulating Craniofacial Development at the 3' End: MicroRNAs and Their Function in Facial Morphogenesis

Defects in craniofacial development represent a majority of observed human birth defects, occurring at a rate as high as 1:800 live births. These defects often occur due to changes in neural crest cell (NCC) patterning and development and can affect non-NCC-derived structures due to interactions between NCCs and the surrounding cell types. Proper craniofacial development requires an intricate array of gene expression networks that are tightly controlled spatiotemporally by a number of regulatory mechanisms. One of these mechanisms involves the action of microRNAs (miRNAs), a class of noncoding RNAs that repress gene expression by binding to miRNA recognition sequences typically located in the 3' UTR of target mRNAs. Recent evidence illustrates that miRNAs are crucial for vertebrate facial morphogenesis, with changes in miRNA expression leading to facial birth defects, including some in complex human syndromes such as 22q11 (DiGeorge Syndrome). In this review, we highlight the current understanding of miRNA biogenesis, the roles of miRNAs in overall craniofacial development, the impact that loss of miRNAs has on normal development and the requirement for miRNAs in the development of specific craniofacial structures, including teeth. From these studies, it is clear that miRNAs are essential for normal facial development and morphogenesis, and a potential key in establishing new paradigms for repair and regeneration of facial defects.

MicroRNA-663 activates the canonical Wnt signaling through the adenomatous polyposis coli suppression

Rheumatoid arthritis (RA) is a symmetrical polyarticular autoimmune disease of unknown etiology. In this present study, we observed that the adenomatous polyposis coli (APC) expression is down-regulated and the expression of microRNA (miR)-663 increased significantly in synovium from RA patients compared with control. Target gene prediction for miR-663 revealed that the mRNA of APC gene, which is a member of the canonical Wnt signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). The result showed that increased miR-663 suppressed the APC expression significantly, and this down-regulation of APC expression triggered the activation of canonical Wnt signaling through accumulation of β-catenin in fibroblast-like synoviocytes (FLS). In addition, increased miR-663 induced the FLS proliferation and the expression MMP3 and fibronectin during disease development. Therefore, miR-663 can be considered as a critical regulator of RA pathogenesis and can be utilized for developing miRNA-based therapeutic agents for RA patients.