Wnt/beta-catenin signaling in oral tissue development and disease

Age-related taste cell generation in circumvallate papillae organoids via regulation of multiple signaling pathways

Sense of taste is central to evaluate food before digestion. Taste stem cells undergo constant differentiation throughout the life. However, the mechanism underlying the generation of taste receptor cells is still not clear. Here, we cultured taste organoids from either Lgr5+ or Lgr5-cells, and found the preferential generation of Car4+ and Gustducin + taste receptor cells in organoids derived from Lgr5+ cells in circumvallate, foliate or fungiform papillae. Taste organoids derived from Lgr5+ cells in circumvallate papillae of neonatal mice showed stronger capacity to generate taste receptor cells compared to the organoids from Lgr5+ cells of the adult circumvallate papillae. Massive transcriptional differences were found in multiple signaling pathways including taste transduction between organoids derived from circumvallate papillae of adult and neonatal mice. Inhibiting the Notch signaling pathway by LY411575 enhanced taste receptor cell generation in organoids from circumvallate papillae and modulated multiple signaling pathways. Thus, we concluded that receptor cell generation in taste organoids was age-related and regulated via multiple signaling pathways.

Berberine mediates root remodeling in an immature tooth with apical periodontitis by regulating stem cells from apical papilla differentiation

Once pulp necrosis or apical periodontitis occurs on immature teeth, the weak root and open root apex are challenging to clinicians. Berberine (BBR) is a potential medicine for bone disorders, therefore, we proposed to apply BBR in root canals to enhance root repair in immature teeth. An in vivo model of immature teeth with apical periodontitis was established in rats, and root canals were filled with BBR, calcium hydroxide or sterilized saline for 3 weeks. The shape of the roots was analyzed by micro-computed tomography and histological staining. In vitro, BBR was introduced into stem cells from apical papilla (SCAPs). Osteogenic differentiation of stem cells from apical papilla was investigated by alkaline phosphatase activity, mineralization ability, and gene expression of osteogenic makers. The signaling pathway, which regulated the osteogenesis of SCAPs was evaluated by quantitative real time PCR, Western blot analysis, and immunofluorescence. In rats treated with BBR, more tissue was formed, with longer roots, thicker root walls, and smaller apex diameters. In addition, we found that BBR promoted SCAPs osteogenesis in a time-dependent and concentration-dependent manner. BBR induced the expression of β-catenin and enhanced β-catenin entering into the nucleus, to up-regulate more runt-related nuclear factor 2 downstream. BBR enhanced root repair in immature teeth with apical periodontitis by activating the canonical Wnt/β-catenin pathway in SCAPs.

Knockdown of Nav1.5 inhibits cell proliferation, migration and invasion via Wnt/β-catenin signaling pathway in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common type of malignant oral cancer that has a high recurrence rate. Voltage-gated sodium channel Nav1.5 was reported to be highly up-regulated in various types of cancers. However, the regulatory mechanism of Nav1.5 in cancers including OSCC still remains elusive. In this study, Nav1.5 was found to be highly expressed in OSCC tissues and cells. Through the analysis of clinical characteristics of patients, we found that the expression level of Nav1.5 was closely related to neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, tumor-node-metastasis stage, and lymph node metastasis. Moreover, we found that Nav1.5 mainly located on the cell membrane as well as cytoplasm and knockdown of Nav1.5 promoted cell apoptosis and decreased proliferation in OSCC. Transwell assay results showed that knockdown of Nav1.5 effectively suppressed the migration and invasion in OSCC. In addition, knockdown of Nav1.5 was found to inhibit the protein and mRNA expression levels of β-catenin, cyclin D1, and c-Myc in the Wnt/β-catenin signaling pathway. In summary, these results indicated that Nav1.5 may be involved in the progression of OSCC through the Wnt/β-catenin signaling pathway.

Inhibition of CD44 sensitizes cisplatin-resistance and affects Wnt/β-catenin signaling in HNSCC cells

CD44 is one of the key cancer stem-like cell (CSC) marker and may have a potential role in tumorigenesis. In this study, we investigated the role of CD44 in prognosis of HNSCC patients, its possible crosstalk with Wnt/β-catenin signaling and modulating cisplatin resistance. We observed increased expression of CD44 in the cut margin of recurrent HNSCC patients were associated with poor prognosis. We observed that inhibition of CD44 by using 1,2,3,4 tetrahydroisoquinoline (THIQ) modulates the expression of Wnt/ β-catenin signaling proteins and further silencing of β-catenin also decreases the expression of CD44. This led us to investigate the possible protein-protein interaction between CD44 and β-catenin. Co-immunoprecipitation study illustrated possible interaction between CD44 and β-catenin which was further confirmed by molecular docking and molecular dynamic (MD) simulation studies. Molecular docking study revealed that one interface amino acid residue Glu642 of β -catenin interacts with Lys92 of CD44 which was also present for 20% of simulation time. Furthermore, we observed that inhibition of CD44 chemosensitizes cisplatin-resistant HNSCC cells towards cisplatin. In conclusion, this study investigated the possible role of CD44 along with Wnt/ β-catenin signaling and their possible therapeutic role to abrogate cisplatin resistance.

SFRP1 in Skin Tumor Initiation and Cancer Stem Cell Regulation with Potential Implications in Epithelial Cancers

Wnt signaling is involved in the regulation of cancer stem cells (CSCs); however, the molecular mechanism involved is still obscure. SFRP1, a Wnt inhibitor, is downregulated in various human cancers; however, its role in tumor initiation and CSC regulation remains unexplored. Here, we used a skin carcinogenesis model, which showed early tumor initiation in Sfrp1^−/− (Sfrp1 knockout) mice and increased tumorigenic potential of Sfrp1^−/− CSCs. Expression profiling on Sfrp1^−/− CSCs showed upregulation of genes involved in epithelial to mesenchymal transition, stemness, proliferation, and metastasis. Further, SOX-2 and SFRP1 expression was validated in human skin cutaneous squamous cell carcinoma, head and neck squamous cell carcinoma, and breast cancer. The data showed downregulation of SFRP1 and upregulation of SOX-2, establishing their inverse correlation. Importantly, we broadly uncover an inverse correlation of SFRP1 and SOX-2 in epithelial cancers that may be used as a potential prognostic marker in the management of cancer.

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Loss of Sfrp1 accelerates murine skin tumor initiation and SCC progression

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Sfrp1 loss enhances in vivo tumorigenic potential of murine skin CSCs

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We found enhanced EMT and Sox-2 in Sfrp1^−/− murine skin SCC

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Sfrp1 and Sox-2 are inversely correlated in multiple human epithelial cancers

Coordination of WNT signaling and ciliogenesis during odontogenesis by piezo type mechanosensitive ion channel component 1

Signal transmission from the mechanical forces to the various intracellular activities is a fundamental process during tissue development. Despite their critical role, the mechanism of mechanical forces in the biological process is poorly understood. In this study, we demonstrated that in the response to hydrostatic pressure (HP), the piezo type mechanosensitive ion channel component 1 (PIEZO1) is a primary mechanosensing receptor for odontoblast differentiation through coordination of the WNT expression and ciliogenesis. In stem cells from human exfoliated deciduous teeth (SHED), HP significantly promoted calcium deposition as well as the expression of odontogenic marker genes, PANX3 and DSPP, and WNT related-genes including WNT5b and WNT16, whereas HP inhibited cell proliferation and enhanced primary cilia expression. WNT signaling inhibitor XAV939 and primary cilia inhibitor chloral hydrate blocked the HP-induced calcium deposition. The PIEZO1 activator Yoda1 inhibited cell proliferation but induced ciliogenesis and WNT16 expression. Interestingly, HP and Yoda1 promoted nuclear translocation of RUNX2, whereas siRNA-mediated silencing of PIEZO1 decreased HP-induced nuclear translocation of RUNX2. Taken together, these results suggest that PIEZO1 functions as a mechanotransducer that connects HP signal to the intracellular signalings during odontoblast differentiation.

Lithium-containing surface pre-reacted glass fillers enhance hDPSC functions and induce reparative dentin formation in a rat pulp capping model through activation of Wnt/β-catenin signaling

Surface pre-reacted glass (S-PRG) fillers are new bioactive molecules used in dental clinic work to fill tooth defects. These fillers release various types of ions (Al⁺³, BO^-3, Na⁺, SiO₃^-2, Sr⁺² and F^-) and exhibit high biocompatibility, antibacterial capability, reduced plaque accumulation, and enhanced osteoblast differentiation. We previously showed that cement of S-PRG fillers could induce tertiary dentin formation in rat models. Previous work also showed that lithium ions can activate the Wnt/β-catenin signaling pathway in vitro and induce dentin formation in pulpotomized teeth in vivo. In the current study, we sought to enhance the effect of S-PRG cement by incorporating LiCl. We show that treatment of human dental pulp stem cells with eluates from S-PRG/LiCl combination cements leads to an upregulation in cell migration, differentiation, and mineralization in vitro. In pulp-capping animal trials, we found that S-PRG/LiCl cements could induce tertiary dentin formation 28-days post-capping. At 7 days post-capping, we identified both β-catenin and Axin2 expression using immunofluorescence, indicative of Wnt/β-catenin signaling activity. In conclusion, S-PRG/LiCl cement is highly effective in promoting human dental pulp stem cells profiles and in enhancing reparative dentin formation in rat teeth through activation of the Wnt/β-catenin canonical signaling pathway. STATEMENT OF SIGNIFICANCE: This is the first study to assess the behavior of S-PRG fillers containing lithium ions on human dental pulp stem cells. We show that this new combination cement promotes positive cell responses by activating the endogenous Wnt/β-catenin signaling pathway in the pulp. The Wnt/β-catenin canonical signaling pathway is involved in many developmental and wound healing processes. The released lithium ions from the S-PRG cement were systematically detected <0.01 mmol/L in our rat model. But it was efficient to induce tertiary dentin formation at the defect site. Since this novel bioactive cement is potentially a promising material for clinical pulp regenerative therapy, future human clinical trials will be needed.

Silibinin's regulation of proliferation and collagen gene expressions of rat pancreatic β-cells cultured on types I and V collagen involves β-catenin nuclear translocation

Extracellular matrix (ECM) molecules have multiple functions; prevention of cytotoxicity, provision of mechanical support, cell adhesive substrates and structural integrity in addition to mediation of cellular signaling. In this study, we report that the proliferation of INS-1 cells cultured on collagen I-coated dishes is enhanced, but it is inhibited on collagen V-coated dishes. Inhibitory proliferation on collagen V-coated is not due to apoptosis induction. Silibinin decreases hepatic glucose production and protects pancreatic β-cells, as a potential medicine for type II diabetes. Silibinin up-regulates the proliferation of cells cultured on both collagen I- and V-coated dishes. Collagen-coating regulates gene expression of collagen in a collagen type-related manner. Silibinin increases mRNA expression of collagen I in the cells on collagen I- and V-coated dishes; however, silibinin decreases collagen V mRNA expression on collagen I- and V-coated dishes. Collagen I-coating significantly enhances nuclear translocation of β-catenin, while collagen V-coating reduces it. Differential effects of silibinin on collagen I mRNA and collagen V mRNA can be accounted for by the finding that silibinin enhances nuclear translocation of β-catenin on both collagen I- and V-coated dishes, since phenomenologically nuclear translocation of β-catenin enhances collagen I mRNA but represses collagen V mRNA. These results demonstrate that nuclear translocation of β-catenin up-regulates proliferation and collagen I gene expression, whereas it down-regulates collagen V gene expression of INS-1 cells. Differential gene expressions of collagen I and V by nuclear β-catenin could be important for understanding fibrosis where collagen I and V may have differential effects.

Gene-gene interaction among cell adhesion genes and risk of nonsyndromic cleft lip with or without cleft palate in Chinese case-parent trios

Background

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect with complex etiology. One strategy for studying the genetic risk factors of NSCL/P is to consider gene–gene interaction (G × G) among gene pathways having a role in craniofacial development. The present study aimed to investigate the G × G among cell adhesion gene pathway.

Methods

We carried out an interaction analysis of eight genes involved in cell adherens junctions among 806 NSCL/P Chinese case‐parent trios originally recruited for a genome‐wide association study (GWAS). Regression‐based approach was used to test for two‐way G × G interaction, while machine learning algorithm was run for exploring both two‐way and multi‐way interaction that may affect the risk of NSCL/P.

Results

A two‐way ACTN1 × CTNNB1 interaction reached the adjusted significance level. The single nucleotide polymorphisms pair composed of rs17252114 (CTNNB1) and rs1274944 (ACTN1) yielded a p value of .0002, and this interaction was also supported by the logic regression algorithm. Higher order interactions involving ACTN1, CTNNB1, and CDH1 were picked out by logic regression, suggesting a potential role in NSCL/P risk.

Conclusion

This study suggests for the first time evidence of both two‐way and multi‐way G × G interactions among cell adhesion genes contributing to the NSCL/P risk.

Expression of β-catenin and MMP-8 in gingival crevicular fluid and gingival tissue indicates the disease severity of patients with chronic periodontitis

The aim of the present study was to investigate the interaction among β-catenin, matrix metalloproteinase-8 (MMP-8) and severity in patients with chronic periodontitis. Both gingival crevicular fluid (GCF) and gingival tissue was collected from 21 healthy control individuals, 21 patients with moderate chronic periodontitis (mCP) and 23 patients with severe chronic periodontitis (sCP). The concentration of MMP-8 in GCF was detected via ELISA and the mRNA levels of β-catenin and MMP-8 in GCF and gingival tissue was detected via reverse transcription-quantitative PCR. The protein levels of β-catenin and MMP-8 in gingival tissue was detected using western blotting and the interaction between β-catenin and MMP-8 in gingival tissue was detected by co-immunoprecipitation. The expression of β-catenin and MMP-8 was significantly higher in the GCF and gingival tissue of patients with chronic periodontitis (mCP and sCP) compared with the control patients. Furthermore, the expression of β-catenin and MMP-8 in GCF and gingival tissue was positively correlated with the clinical attachment level. In addition, a positive interaction was identified between β-catenin and MMP-8, and the expression of β-catenin was positively correlated with the expression of MMP-8 in GCF and gingival tissue. The CGF and gingival tissue expression of β-catenin and MMP-8 may indicate disease severity in patients with chronic periodontitis.

Role of osteoprotegerin in the regulation of dental epithelial‑mesenchymal signaling during tooth development

Dental epithelial-mesenchymal signaling is crucial for tooth development, but the detailed mechanism is not fully understood. Using microarray analysis, it was revealed that the expression of osteoprotegerin, an important factor regulating bone remodeling, significantly increased after removal of the dental epithelium. Immunohistochemical staining revealed that osteoprotegerin expression within the dental mesenchyme was quite low during the prenatal period, but significantly increased after birth. To investigate the influence of osteoprotegerin upon tooth development, first-molar tooth germs from embryonic day 14.5 (E14.5) Chinese Kunming mice were treated with different concentrations of osteoprotegerin. It was revealed that osteoprotegerin could inhibit the expression of odontogenic markers while promoting the expression of osteogenic markers, thereby disrupting tooth morphogenesis. These findings were further supported by in vitro and in vivo cultures. Finally, quantitative reverse transcription-polymerase chain reaction and immunofluorescence studies revealed that, after osteoprotegerin treatment, the activity of the wingless/integrated (Wnt)/β-catenin pathway increased, indicating that increased osteoprotegerin expression in prenatal tooth development could lead to uncontrolled upregulation of the Wnt/β-catenin pathway.

[Expression patterns of ectodysplasin and ectodysplasin receptor during early dental development in zebrafish]

OBJECTIVE

This study aims to study the expression patterns of ectodysplasin (EDA) and ectodysplasin receptor (EDAR) during the early development of zebrafish and provide a foundation for further research of the Eda signaling pathway in tooth development.

METHODS

Total RNA was extracted from zebrafish embryos at 48 hours postfertilization (hpf) and then reverse transcribed for cDNA library generation. The corresponding RNA polymerase was selected for the synthesis of the digoxin-labeled antisense mRNA probe of zebrafish pharyngeal tooth specific marker dlx2b and Eda signaling-associated genes eda and edar in vitro. The three sequences were ligated into a pGEMT vector with a TA cloning kit, and polymerase chain reaction (PCR) was applied to linearize the plasmid. The resultant PCR sequences were used as templates for synthesizing Dig-labeled mRNA probe dlx2b, eda, and edar. Zebrafish embryos were collected at 36, 48, 56, 60, 72, and 84 hpf, then whole mount in situ hybridization was performed for the detection of eda and edar expression patterns. Then, their expression patterns at 72 hpf were compared with the expression pattern of dlx2b.

RESULTS

The mRNA antisense probes of dlx2b, eda, and edar were successfully obtained. The positive signals of eda and edar were observed in zebrafish pharyngeal tooth region at 48-72 hpf and thus conform to the signals of dlx2b in the positive regions.

CONCLUSIONS

The ligand eda and edar, which are associated with the Eda signaling pathway, are strongly expressed only at the pharyngeal tooth region in zebrafish from tooth initiation to the morphogenesis stage. Thus, the Eda signaling pathway may be involved in the regulation of the early development of zebrafish pharyngeal teeth.

Current Research Progress on Long Noncoding RNAs Associated with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of mortality among cancers. It has been found that long noncoding RNAs (lncRNAs) are involved in many human cancers, including liver cancer. It has been identified that carcinogenic and tumor-suppressing lncRNAs are associated with complex processes in liver cancer. These lncRNAs may participate in a variety of pathological and biological activities, such as cell proliferation, apoptosis, invasion, and metastasis. Here, we review the regulation and function of lncRNA in liver cancer and evaluate the potential of lncRNA as a new goal for liver cancer.

Berberine Accelerates Odontoblast Differentiation by Wnt/β-Catenin Activation

Berberine, a Chinese medical herbal extract, plays a key role in antidiabetic, antiangiogenesis, anti-inflammatory, antimicrobial, anticancer, and antihypercholesterolemic. Our previous studies revealed that berberine exerted odontoprotective effect by increasing odontoblast differentiation. However, the mechanisms involved in the odontoprotective effect of berberine have not been fully explored. The Wnt/β-catenin pathway is involved in odontoblast differentiation of dental pulp stem cells (DPSCs). If β-catenin is nuclear translocation, the Wnt/β-catenin pathway is activation. In this study, DPSCs were treated with or without berberine. Then, we examined the accelerative effects of berberine on odontoblast differentiation and mineralized nodules formation by real-time polymerase chain reaction, alizarin red S staining, and alkaline phosphatase staining. In addition, while treated with berberine, β-catenin translocated to the nucleus evaluated by western blot and immunofluorescent staining. Our results revealed that berberine functions as a promoter of odontoblast differentiation by promoting Wnt/β-catenin pathway, suggesting that it may be useful in guiding therapeutic strategies for the treatment of dental caries.

Nerigoside suppresses colorectal cancer cell growth and metastatic potential through inhibition of ERK/GSK3β/β-catenin signaling pathway

BACKGROUND

Nerigoside (NG), a cardenolide isolated from a commonfolk medicine, Nerium oleander Linn. (Apocynaceae), has not been explored for its biological effects. To date, cardenolides have received considerable attention in pharmacology studies due to their direct effects of apoptosis-induction or growth-inhibitory against tumor in vitro and in vivo. Whether and how NG exerts anticancer effects against colorectal cancer remains to be elucidated.

PURPOSE

The aim of this study was to investigate the anticancer effect of NG in human colorectal cancer cells.

METHODS

To test anticancer effect, we compared potency of NG in two colorectal cancer cell lines, HT29 and SW620 by WST-1 and colony proliferation assays. And we investigated mechanism of anticancer activities by analyzing players in apoptotic and ERK/GSK3β/β-catenin signaling pathways in HT29 and SW620 cells treated with NG.

RESULTS

In this study, we showed that NG markedly suppressed the cell viability and colony formation of colorectal cancer cells HT29 and SW620, with no significant toxic effect on non-cancer cells NCM460. Annexin V-FITC/PI and CFSE labeling results revealed that NG suppressed cell proliferation in low concentration, along with reducing expression of PCNA, while NG induced apoptosis in high concentration,. Meanwhile, NG significantly arrested cell migration by reversal of EMT and cell cycle on G2/M. Then, we found that the ERK and GSK3β/β-catenin signaling pathway were noticeably blocked in CRC cells after treatment with NG. According to western blot, NG upregulated the expression of p-GSK3β/GSK3β and decreased especially the expression of β-catenin in nuclear. In addition, Wnt signaling and its target genes were suppressed in response to NG. Then, the Ser9 phosphorylation of GSK3β can be reduced / raised by GÖ 6983 / LiCl, respectively. Thus, we further confirmed that the GSK3β/β-catenin axis is involved in NG-prevented cell proliferation.

CONCLUSION

NG inhibited the growth of colorectal cancer cells by suppressing ERK/GSK3β/β-catenin signaling pathway. And the GSK3β/β-catenin axis is involved in preventing cell proliferation and migration by NG-treatment. These results suggest that NG may be used to treat colorectal cancer, with better outcome by combining with GSK3β inhibitor to block Wnt pathway.

KHC-4 inhibits β-catenin expression in prostate cancer cells

KHC-4 is a 2-phenyl-4-quinolone analogue that exhibits anticancer activity. Aberrant activation of β-catenin signaling contributes to prostate cancer development and progression. Therefore, targeting β-catenin expression could be a useful approach to treating prostate cancer. We found that KHC-4 can inhibit β-catenin expression and its signaling pathway in DU145 prostate cancer cells. Treatment with KHC-4 decreased total β-catenin expression and concomitantly decreased β-catenin levels in both the cytoplasm and nucleus of cells. KHC-4 treatment also inhibited β-catenin expression and that of its target proteins, PI3K, AKT, GSK3β and TBX3. We monitored the stability of β-catenin with the proteasomal inhibitor, MG132, in DU145 cells and found that MG132 reversed KHC-4-induced proteasomal β-catenin degradation. We verified CDK1/β-catenin expression in KHC-4 treated DU145 cells. We found that roscovitine treatment reversed cell proliferation by arresting the cell cycle at the G2/M phase and β-catenin expression caused by KHC-4 treatment. We suggest that KHC-4 inhibits β-catenin signaling in DU145 prostate cancer cells.

The Role of the Wnt Signaling Pathway in Upper Jaw Development of Chick Embryo

Cleft lip with or without cleft palate (CLP) usually results from a failure of the medial nasal prominences to fuse with the lateral and maxillary prominences. This failure inhibits facial morphogenesis regulated by several major morphogenetic signaling pathways. We hypothesized that CLP results from the failure of the Wnt signaling pathway. To examine whether Wnt signaling can influences upper jaw development, we applied beads soaked with Dickkopf-1 (Dkk-1), Alsterpaullone (AL) or Wnt3a to the right side of the maxillary prominence of the chick embryo. The embryo showed a defect of the maxilla on the treated side, and skeletal staining revealed hypoplasia of the premaxilla and palatine bone as a result of Dkk-1-soaked bead implantation. 5-bromo-2'-deoxyuridine (BrdU)-positive cell numbers in the treated maxillary prominence were significantly lower at both 24 and 48 hr after implantation. Down-regulation of the expression of Bmp4, Tbx22, Sox9, and Barx1 was confirmed in the maxillary prominence treated with Dkk-1, which indicated that the deformity of the maxillary bone was controlled by gene targets of the Wnt signaling pathway. Expression of N-cadherin was seen immunohistochemically in the maxillary prominences of embryos at 6 hr and increased at 24 hr after AL treatment. Wnt signaling enhanced by AL or Wnt3a up-regulated the expression levels of Msx1, Bmp4, Tbx22, Sox9, and Barx1. Our data suggest that the Wnt signaling pathway regulates maxillary morphogenesis and growth through Bmp4, Tbx22, Sox9, and Barx1. Wnt signaling might regulate N-cadherin expression via Msx1, resulting in cell aggregation for osteochondrogenesis.

Depletion of WNT10A Prevents Tumor Growth by Suppressing Microvessels and Collagen Expression

Background: We recently reported that WNT10A plays a pivotal role in wound healing by regulating collagen expression/synthesis, as the depletion of WNT10A dramatically delays skin ulcer formation. WNT signaling also has a close correlation with the cancer microenvironment and proliferation, since tumors are actually considered to be 'unhealing' or 'overhealing' wounds. To ascertain the in vivo regulatory functions of WNT10A in tumor growth, we examined the net effects of WNT10A depletion using Wnt10a-deficient mice (Wnt10a ^-/-). Methods and Results: We subjected C57BL/6J wild-type (WT) or Wnt10a ^-/- mice to murine melanoma B16-F10 cell transplantation. Wnt10a ^-/- mice showed a significantly smaller volume of transplanted melanoma as well as fewer microvessels and less collagen expression and more necrosis than WT mice. Conclusions: Taken together, our observations suggest that critical in vivo roles of Wnt10a-depleted anti-stromagenesis prevent tumor growth, in contrast with true wound healing/scarring.

Epithelial Cdc42 Deletion Induced Enamel Organ Defects and Cystogenesis

Cdc42, a Rho family small GTPase, regulates cytoskeleton organization, vesicle trafficking, and other cellular processes in development and homeostasis. However, Cdc42's roles in prenatal tooth development remain elusive. Here, we investigated Cdc42 functions in mouse enamel organ. Cdc42 showed highly dynamic temporospatial patterns in the developing enamel organ, with robust expression in the outer enamel epithelium, stellate reticulum (SR), and stratum intermedium layers. Strikingly, epithelium-specific Cdc42 deletion resulted in cystic lesions in the enamel organ. Cystic lesions were first noted at embryonic day 15.5 and progressively enlarged during gestation. At birth, cystic lesions occupied the bulk of the entire enamel organ, with intracystic erythrocyte accumulation. Ameloblast differentiation was retarded upon epithelial Cdc42 deletion. Apoptosis occurred in the Cdc42 mutant enamel organ prior to and synchronously with cystogenesis. Transmission electron microscopy examination showed disrupted actin assemblies, aberrant desmosomes, and significantly fewer cell junctions in the SR cells of Cdc42 mutants than littermate controls. Autophagosomes were present in the SR cells of Cdc42 mutants relative to the virtual absence of autophagosome in the SR cells of littermate controls. Epithelium-specific Cdc42 deletion attenuated Wnt/β-catenin and Shh signaling in dental epithelium and induced aberrant Sox2 expression in the secondary enamel knot. These findings suggest that excessive cell death and disrupted cell-cell connections may be among multiple factors responsible for the observed cystic lesions in Cdc42 mutant enamel organs. Taken together, Cdc42 exerts multidimensional and pivotal roles in enamel organ development and is particularly required for cell survival and tooth morphogenesis.

FoxO6 regulates Hippo signaling and growth of the craniofacial complex

The mechanisms that regulate post-natal growth of the craniofacial complex and that ultimately determine the size and shape of our faces are not well understood. Hippo signaling is a general mechanism to control tissue growth and organ size, and although it is known that Hippo signaling functions in neural crest specification and patterning during embryogenesis and before birth, its specific role in postnatal craniofacial growth remains elusive. We have identified the transcription factor FoxO6 as an activator of Hippo signaling regulating neonatal growth of the face. During late stages of mouse development, FoxO6 is expressed specifically in craniofacial tissues and FoxO6-/- mice undergo expansion of the face, frontal cortex, olfactory component and skull. Enlargement of the mandible and maxilla and lengthening of the incisors in FoxO6-/- mice are associated with increases in cell proliferation. In vitro and in vivo studies demonstrated that FoxO6 activates Lats1 expression, thereby increasing Yap phosphorylation and activation of Hippo signaling. FoxO6-/- mice have significantly reduced Hippo Signaling caused by a decrease in Lats1 expression and decreases in Shh and Runx2 expression, suggesting that Shh and Runx2 are also linked to Hippo signaling. In vitro, FoxO6 activates Hippo reporter constructs and regulates cell proliferation. Furthermore PITX2, a regulator of Hippo signaling is associated with Axenfeld-Rieger Syndrome causing a flattened midface and we show that PITX2 activates FoxO6 expression. Craniofacial specific expression of FoxO6 postnatally regulates Hippo signaling and cell proliferation. Together, these results identify a FoxO6-Hippo regulatory pathway that controls skull growth, odontogenesis and face morphology.

The Antihelminthic Niclosamide Inhibits Cancer Stemness, Extracellular Matrix Remodeling, and Metastasis through Dysregulation of the Nuclear β-catenin/c-Myc axis in OSCC

Niclosamide is an oral chlorinated salicylanilide antihelminthic agent with potential anticancer activity suggested in several cancer types, however, its anticancer action and likely molecular mechanism in malignant oral cells remain unclear. In the present study, we demonstrated that ALDH+ human oral squamous cell carcinoma (OSCC) cells are characterized by upregulated expression of the pluripotency transcription factors OCT4, Nanog and Sox2, as well as exhibit enhanced cancer stemness, as demonstrated by enhanced tumorsphere formation. We also showed that niclosamide effectively inhibits activation of the Wnt/β-catenin signaling pathway by targeting multiple components of this pathway, including downregulating the expression β-catenin, Dishevelled 2 (DVL2), phosphorylated glycogen synthase kinase-3β (p-GSK3β) and Cyclin D1, in human OSCC SCC4 and SCC25 cell lines, as well as reduced the formation of primary and secondary tumorspheres. In addition, we showed that niclosamide inhibits the epithelial-to-mesenchymal transition (EMT), migration and colony formation of the OSCC cells, by dose-dependently upregulating E-cadherin and the tissue inhibitor of metalloproteinases 2 (TIMP2) mRNA levels, while reducing the expression levels of vimentin, snail, MMP2 and MMP9 mRNA. These anticancer activities of niclosamide were similar to those caused by interference with nuclear β-catenin/c-Myc expression using the siRNA transfection. Finally, we demonstrated that niclosamide inhibits cisplatin-induced OSCC stem cell enrichment and enhances sensitivity to cisplatin in ALDH+ tumorspheres. These experimental data, combined with accumulated evidence, are suggestive of the potential and efficacy of niclosamide in the treatment of OSCC.

Nkd2 promotes the differentiation of dental follicle stem/progenitor cells into osteoblasts

Dental follicle stem/progenitor cells have the potential to undergo osteogenesis. naked cuticle homolog 2 (Nkd2) is a signal-inducible feedback antagonist of the canonical Wnt signaling pathway. The purpose of the present study was to investigate the function of Nkd2 in the differentiation of dental follicle stem/progenitor cells (DFSCs) into osteoblasts. Immunohistochemistry, reverse transcription-quantitative polymerase chain reaction and western blotting were employed to detect Nkd2 expression in rat DFSCs. In addition, rat DFSCs (rDFSCs) were transfected with small interfering RNAs to examine the effect of Nkd2 on the differentiation of these cells into osteoblasts. Furthermore, the function of Nkd2 in the Wnt/β-catenin pathway in rDFSCs was investigated using β-catenin/T-cell factor luciferase activity assays and western blotting. It was revealed that the expression of Nkd2 was upregulated during the differentiation of rDFSCs into osteoblasts. Furthermore, osteoblast differentiation ability and Wnt/β-catenin pathway activity were significantly decreased in Nkd2-silenced rDFSCs compared with the si-NC group (P<0.05 and P<0.001, respectively). The results suggest that Nkd2 promotes the differentiation of rDFSCs into osteoblasts through Wnt/β-catenin signaling.

[The role of Wnt/β-catenin signaling pathway in ameloblastoma formation]

The aim of the study was to assess the role of the canonical Wnt/β-catenin signaling pathway in the formation and clinical course of various histological variants of ameloblastoma.

MATERIAL AND METHODS

76 cases of ameloblastoma were investigated, the average age of the patients was 46 years. There were 49 (64.5%) cases of recurrence of the disease. Tissue antigens were determined using monoclonal rabbit antibodies to Ki-67 and β-catenin.

RESULTS

it was found correlation between the proliferative activity of ameloblastoma cells and the intranuclear localization of β-catenin, indicating the activation of the Wnt/β-catenin-signaling pathway. It was shown that the nuclear localization of β-catenin is positively correlated with the recurrence.

CONCLUSION

The Wnt/β-catenin signaling pathway is involved in a formation and progression of ameloblastoma.

The Changing Landscape in the Genetic Etiology of Human Tooth Agenesis

Despite much progress in understanding the genetics of syndromic tooth agenesis (TA), the causes of the most common, isolated TA remain elusive. Recent studies have identified novel genes and variants contributing to the etiology of TA, and revealed new pathways in which tooth development genes belong. Further, the use of new research approaches including next-generation sequencing has provided increased evidence supporting an oligogenic inheritance model for TA, and may explain the phenotypic variability of the condition. In this review, we present current knowledge about the genetic mechanisms underlying syndromic and isolated TA in humans, and highlight the value of incorporating next-generation sequencing approaches to identify causative and/or modifier genes that contribute to the etiology of TA.

Methacholine induces extracellular matrix production by human airway smooth muscle cells through β-catenin signaling

Altered extracellular matrix (ECM) production by airway smooth muscle cells (ASMCs) is an important feature of airway remodeling. Muscarinic receptor agonists contribute to ECM production in vivo, but the mechanisms involved remain unclear. This study attempted to investigate the role of methacholine in promoting ECM production by human ASMCs (HASMCs) and the underlying mechanism. We found that methacholine induced the expression of collagen I protein and multiple ECM genes. β-catenin signaling was activated in this process upon GSK3β phosphorylation, leading to upregulation of total and active β-catenin. Silencing β-catenin by specific small interfering RNA (siRNA) or with the β-catenin inhibitor, PKF115-584, decreased collagen I expression. Conversely, overexpression of active β-catenin by adenoviruses carrying the S33Y-β-catenin mutant increased the methacholine-induced collagen I expression. Furthermore, methacholine induced TGF-β expression in HASMCs, while pan-TGF-β-neutralizing antibody only partially decreased collagen I expression. These findings suggest that methacholine induced ECM production through β-catenin signaling and partially through TGF-β.

An Update on the Sense of Taste in Chickens: A Better Developed System than Previously Appreciated

Taste is important in guiding nutritive choices and motivating food intake. The sensory organs for taste are the taste buds, that transduce gustatory stimuli into neural signals. It has been reported that chickens have a low taste bud number and thus low taste acuity. However, more recent studies indicate that chickens have a well-developed taste system and the reported number and distribution of taste buds may have been significantly underestimated. Chickens, as a well-established animal model for research, are also the major species of animals in the poultry industry. Thus, a clear understanding of taste organ formation and the effects of taste sensation on nutrition and feeding practices is important for improving livestock production strategies. In this review, we provide an update on recent findings in chicken taste buds and taste sensation indicating that the chicken taste organ is better developed than previously thought and can serve as an ideal system for multidisciplinary studies including organogenesis, regenerative medicine, feeding and nutritional choices.

Critical in vivo roles of WNT10A in wound healing by regulating collagen expression/synthesis in WNT10A-deficient mice

Background

We have reported that WNT10A plays a critical role in the growth of fibroblasts/myofibroblasts and microvascular endothelial cells, i.e.; wound healing/scarring. To ascertain the in vivo regulatory, central functions of WNT10A, we examined the net effects of WNT10A depletion using WNT10A-deficient mice (WNT10A^–/–).

Methods and results

We generated WNT10A^–/–mice, displaying a range of unique phenotypes of morpho/organogenetic failure, such as growth retardation, alopecia, kyphosis and infertility, and then focused on the functions of WNT10A in wound healing. We subjected C57BL/6J wild-type (WT) or WNT10A^–/–mice to skin ulcer formation. The WNT10A^–/–mice had significantly larger injured areas and delayed wound healing, which were associated with (a) a smaller number of fibroblasts/myofibroblasts and microvessels; and (b) more reduced expression and synthesis of collagen, compared with WT mice with intact WNT10A expression, especially in those with activated myofibroblasts.

Conclusions

These observations indicate that WNT10A signaling can play a pivotal in vivo role in wound healing by regulating the expression and synthesis of collagen, as one of fibrogenic factors, at least in part, and critical in vivo roles of WNT10A-mediated effective wound healing are extremely closely associated with collagen expression.

Downregulation of Frizzled-7 induces the apoptosis of hepatocellular carcinoma cells through inhibition of NF-κB

The aim of the present study was to investigate the functional role of Frizzled-7 (FZD7) in the apoptosis of hepatoma cells. HepG2 and Huh-7 hepatocellular carcinoma (HCC) cell lines with FZD7 expression were selected for use in the present study. The small hairpin RNA (shRNA) eukaryotic expression vector specific to FZD7 was constructed using gene recombination, and was then transfected into HepG2 and Huh-7 hepatoma cell lines using Lipofectamine 2000 to assess whether the downregulation of FZD7 could affect the proliferative ability of these cells. The results demonstrated that the downregulation of FZD7 expression significantly inhibited the proliferative ability of both cell types through the induction of cell apoptosis, as evidenced using Cell Counting kit-8 assays and flow cytometry. Furthermore, the western blotting results demonstrated that silencing of FZD7 increased the activities of caspase-3 and caspase-9. These increases were also associated with the downregulation of the inhibitor of the apoptosis protein family. Additionally, it was revealed that silencing of FZD7 expression caused the downregulation of apoptosis regulator Bcl-2 and Bcl-XL in HepG2, and Huh-7 cells, as determined through western blot analysis and reverse transcription-quantitative polymerase chain reaction. In the following work, ELISA and western blot analysis revealed that the knockdown of FZD7 inhibited the expression and activities of nuclear factor-κB (NF-κB) p65. Furthermore, it was demonstrated that the expression levels of phosphylated-Smad2/3 were markedly upregulated in sh-FZD7-transfected HepG2 and Huh-7 cells. Then, shRNA eukaryotic expression vector specific to transforming growth factor (TGF)-β receptor II was transfected into both cell lines to investigate the association between the TGF-β/Smad signaling pathway and NF-κB p65. Notably, when the TGF-β/Smad signaling pathway was inhibited, no significant differences in the cell apoptosis rate and NF-κB expression levels were identified in HCC cells. Overall, the results of the present study suggest that the shRNA-mediated knockdown of FZD7 induces apoptosis of hepatoma cell lines through the inhibition of NF-κB. In addition, the TGF-β/Smad signaling pathway appeared to partially participate in the underlying molecular mechanism of FZD7 in HCC.

Expanding the Oro-Dental and Mutational Spectra of Kabuki Syndrome and Expression of KMT2D and KDM6A in Human Tooth Germs

Kabuki syndrome is a rare genetic disorder characterized by distinct dysmorphic facial features, intellectual disability, and multiple developmental abnormalities. Despite more than 350 documented cases, the oro-dental spectrum associated with kabuki syndrome and expression of KMT2D (histone-lysine N-methyltransferase 2D) or KDM6A (lysine-specific demethylase 6A) genes in tooth development have not been well defined. Here, we report seven unrelated Thai patients with Kabuki syndrome having congenital absence of teeth, malocclusion, high-arched palate, micrognathia, and deviated tooth shape and size. Exome sequencing successfully identified that six patients were heterozygous for mutations in KMT2D, and one in KDM6A. Six were novel mutations, of which five were in KMT2D and one in KDM6A. They were truncating mutations including four frameshift deletions and two nonsense mutations. The predicted non-functional KMT2D and KDM6A proteins are expected to cause disease by haploinsufficiency. Our study expands oro-dental, medical, and mutational spectra associated with Kabuki syndrome. We also demonstrate for the first time that KMT2D and KDM6A are expressed in the dental epithelium of human tooth germs.

miR‑377 targets CUL4A and regulates metastatic capability in ovarian cancer

The incidence and recurrence rates of ovarian cancer are still high, and once the disease metastasizes, it is nearly always fatal. Cullin 4A (CUL4A) serves a significant role in tumourigenesis and tumour progression; however, the effect and mechanisms underlying CUL4A overexpression are still unknown. The role of microRNAs (miRs) in the regulation of metastatic capability in ovarian cancer cell lines was investigated. The interaction between miR‑377 and CUL4A was investigated using bioinformatics analyses and dual‑luciferase reporter assays. Furthermore, miR‑377 mRNA and protein levels were detected using reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively and cell migration and invasion were detected using a Transwell assay. Results revealed that CUL4A expression was negatively associated with miR‑377 levels in ovarian cancer tissues and cell lines. Through in silico analysis, the targeting effect of miR‑377 on CUL4A was verified. Ectopic expression of miR‑377 in SKOV3 cells downregulated the level of CUL4A, and significantly reduced the migratory ability of the cells. miR‑377 overexpression led to reduced activity of the Wnt/β‑catenin signaling pathway, and regulated the expression of matrix metalloproteinase‑2, and 9, and epithelial‑mesenchymal transition (EMT)‑associated protein. These results suggested that miR‑377 is a significant negative regulator of CUL4A that controls cancer cell progression in ovarian cancer cell lines.

Association of the WNT3 Variations and the Risk of Non-Syndromic Cleft Lip and Palate in a Population of Iranian Infants

BACKGROUND

Nonsyndromic cleft lip and/or palate (NSCL/P) is the most common orofacial birth defect, often attributed to ethnic and environmental differences. Up to now, linkage analyses and genome-wide association studies have identified several genomic susceptibility regions for NSCL/P. The WNT genes including WNT3 are strong candidates for NSCL/P, since they are involved in regulating mid-face development and upper lip fusion. This study tested association of the WNT3 polymorphisms, rs-3809857 G/T and rs9890413 G/A, with the risk of NSCL/P in a population of Iranian infants.

METHODS

The allelic and genotypic frequencies for each participant were determined in 113 unrelated Iranian subjects with NSCL/P and 220 control subjects using PCR and restriction fragment length polymorphism (RFLP) methods. A p-value of ≤0.05 was considered statistically significant.

RESULTS

The WNT3 rs3809857 GT genotype was significantly lower (p=0.039, OR=0.55, 95% CI=0.30-0.97) in the NSCL/P (21.2%) than the control group (30.42%). For the WNT3 rs9890413 G/A polymorphism, neither genotype nor allele frequencies were significantly different between the case and control groups.

CONCLUSION

Our results indicated that the WNT3 rs3809857 GT genotype may have a protective effect against NSCL/P in Iranian population.

Role of WNT10A in failure of tooth development in humans and zebrafish

BACKGROUND

Oligodontia is a severe form of tooth agenesis characterized by the absence of six or more permanent teeth. Oligodontia has complex etiology and variations in numerous genes have been suggested as causal for the condition.

METHODS

We applied whole-exome sequencing (WES) to identify the cause of oligodontia in a 9-year-old girl missing 11 permanent teeth. Protein modeling and functional analysis in zebrafish were also performed to understand the impact of identified variants on the phenotype.

RESULTS

We identified a novel compound heterozygous missense mutation in WNT10A (c.637G>A:p.Gly213Ser and c.1070C>T:p.Thr357Ile) as the likely cause of autosomal recessive oligodontia in the child. Affected residues are located in conserved regions and variants are predicted to be highly deleterious for potentially destabilizing the protein fold and inhibiting normal protein function. Functional studies in zebrafish embryos showed that wnt10a is expressed in the craniofacies at critical time points for tooth development, and that perturbations of wnt10a expression impaired normal tooth development and arrested tooth development at 5 days postfertilization (dpf). Furthermore, mRNA expression levels of additional tooth development genes were directly correlated with wnt10a expression; expression of msx1, dlx2b, eda, and axin2 was decreased upon wnt10a knockdown, and increased upon wnt10a overexpression.

CONCLUSIONS

Our results reveal a novel compound heterozygous variant in WNT10A as pathogenic for oligodontia, and demonstrate that perturbations of wnt10a expression in zebrafish may directly and/or indirectly affect tooth development recapitulating the agenesis phenotype observed in humans.

RNA-Seq analysis on chicken taste sensory organs: An ideal system to study organogenesis

RNA-Seq is a powerful tool in transcriptomic profiling of cells and tissues. We recently identified many more taste buds than previously appreciated in chickens using molecular markers to stain oral epithelial sheets of the palate, base of oral cavity, and posterior tongue. In this study, RNA-Seq was performed to understand the transcriptomic architecture of chicken gustatory tissues. Interestingly, taste sensation related genes and many more differentially expressed genes (DEGs) were found between the epithelium and mesenchyme in the base of oral cavity as compared to the palate and posterior tongue. Further RNA-Seq using specifically defined tissues of the base of oral cavity demonstrated that DEGs between gustatory (GE) and non-gustatory epithelium (NGE), and between GE and the underlying mesenchyme (GM) were enriched in multiple GO terms and KEGG pathways, including many biological processes. Well-known genes for taste sensation were highly expressed in the GE. Moreover, genes of signaling components important in organogenesis (Wnt, TGFβ/ BMP, FGF, Notch, SHH, Erbb) were differentially expressed between GE and GM. Combined with other features of chicken taste buds, e.g., uniquely patterned array and short turnover cycle, our data suggest that chicken gustatory tissue provides an ideal system for multidisciplinary studies, including organogenesis and regenerative medicine.

A Reciprocal Interaction between β-Catenin and Osterix in Cementogenesis

Although accumulating evidence indicates that both β-catenin and osterix (Osx) are essential for bone and tooth development, few studies have investigated the interaction of these two key proteins in the context of cementogenesis. In this study, we used transgenic mice with constitutively active β-catenin and inactive Osx in the dental mesenchyme to address this question. We found that cementoblasts with constitutively active β-catenin require Osx to produce excessive cellular cementum, and that ablation of Osx prevents this abnormal accumulation. Importantly, cementoblasts transduced with retrovirus expressing constitutively active β-catenin exhibited upregulation of Osx expression through direct binding to the promoter region of Osx. Osx regulates Lef1 expression and consequently could regulate T-cell factor/lymphoid enhancer factor (Tcf/Lef) binding activity in Wnt/β-catenin signaling. However, the loss of Tcf/Lef binding activity by Osx ablation was not rescued by transduction of retrovirus expressing constitutively active β-catenin or ectopic Lef1 overexpression. These results suggest that the Tcf/Lef binding activity of Wnt/β-catenin signaling is Osx-dependent during cementogenesis. Moreover, Osx differentially regulates the expression of various Tcf family members, suggesting that Osx regulates cementogenesis by utilizing various Tcf/Lef-dependent mechanisms. This is the first report to show that downstream Osx signaling through Tcf/Lefs is critical for cementogenesis.

Expression of planar cell polarity genes during mouse tooth development

OBJECTIVE

Planar cell polarity (PCP) refers to the cell polarity across the tissue plane and controls various cell behaviors and structures. Although the expression of several PCP signaling components has been detected in tooth germs, knowledge of the gene expression patterns of these PCP components during tooth development remains incomplete. The aim of this study is to characterize the temporal and spatial changes in PCP gene expression during tooth development.

DESIGN

Expression of Celsr1 and 2, Fzd3 and 6, Vangl1 and 2, and Dvl1-3 genes was analyzed in mouse molar germs from the bud to the bell stage using in situ hybridization.

RESULTS

At the bud stage, all target genes were expressed in all areas of the tooth bud. In the enamel organ at the cap stage, expression of Fzd3 was suppressed in the enamel knot, whereas Fzd6 was strongly expressed there. Expression of Vangl2 was strongly expressed in the inner dental epithelium from the cap stage onwards. In the inner dental epithelium, strong expression of Fzd3, Dvl2 and Vangl2 was noted at the early bell stage, and of Celsr1, Fzd3, Fzd6, Vangl2 and Dvl2 at the bell stage. Furthermore, differentiated odontoblasts strongly expressed Celsr1, Vangl2, and Dvl2.

CONCLUSION

The gene expression patterns delineated in this study improve our understanding of the role(s) of PCP components during tooth development.

Axin2-expressing cells differentiate into reparative odontoblasts via autocrine Wnt/β-catenin signaling in response to tooth damage

In non-growing teeth, such as mouse and human molars, primary odontoblasts are long-lived post-mitotic cells that secrete dentine throughout the life of the tooth. New odontoblast-like cells are only produced in response to a damage or trauma. Little is known about the molecular events that initiate mesenchymal stem cells to proliferate and differentiate into odontoblast-like cells in response to dentine damage. The reparative and regenerative capacity of multiple mammalian tissues depends on the activation of Wnt/β-catenin signaling pathway. In this study, we investigated the molecular role of Wnt/β-catenin signaling pathway in reparative dentinogenesis using an in vivo mouse tooth damage model. We found that Axin2 is rapidly upregulated in response to tooth damage and that these Axin2-expressing cells differentiate into new odontoblast-like cells that secrete reparative dentine. In addition, the Axin2-expressing cells produce a source of Wnt that acts in an autocrine manner to modulate reparative dentinogenesis.

Genetic alterations in mesiodens as revealed by targeted next-generation sequencing and gene co-occurrence network analysis

OBJECTIVE

Mesiodens is the most common type of supernumerary tooth which includes a population prevalence of 0.15%-1.9%. Alongside evidence that the condition is heritable, mutations in single genes have been reported in few human supernumerary tooth cases. Gene sequencing methods in tradition way are time-consuming and labor-intensive, whereas next-generation sequencing and bioinformatics are cost-effective for large samples and target sizes.

MATERIALS AND METHODS

We describe the application of a targeted next-generation sequencing (NGS) and bioinformatics approach to samples from 17 mesiodens patients. Subjects were diagnosed on the basis of panoramic radiograph. A total of 101 candidate genes which were captured custom genes were sequenced on the Illumina HiSeq 2500. Multistep bioinformatics processing was performed including variant identification, base calling, and in silico analysis of putative disease-causing variants.

RESULTS

Targeted capture identified 88 non-synonymous, rare, exonic variants involving 42 of the 101 candidate genes. Moreover, we investigated gene co-occurrence relationships between the genomic alterations and identified 88 significant relationships among 18 most recurrent driver alterations.

CONCLUSION

Our search for co-occurring genetic alterations revealed that such alterations interact cooperatively to drive mesiodens. We discovered a gene co-occurrence network in mesiodens patients with functionally enriched gene groups in the sonic hedgehog (SHH), bone morphogenetic proteins (BMP), and wingless integrated (WNT) signaling pathways.

KLK4 silencing inhibits the growth of oral squamous cell carcinoma through Wnt/β-catenin signaling pathway

Oral squamous cell carcinoma (OSCC) is a malignancy that largely impacts the quality of people's daily life. Kallikrein-related peptidase 4 (KLK4) is highly expressed in OSCC; however, its roles in OSCC cells are unclear. In the present study, the effect of KLK4 silencing on the growth of OSCC cells was investigated. Our study showed that the proliferation and colony formation of OSCC cells was inhibited by KLK4 silencing and their cell cycle was arrested. Additionally, apoptosis of OSCC cells was enhanced by KLK4 silencing, with increased protein levels of cleaved PARP, cleaved caspase-3, Bax and decreased levels of Bcl-2. KLK4 silencing inhibited the Wnt/β-catenin signaling pathway, as evidence by decreased protein levels of Wnt1, β-catenin, reduced GSK-3β phosphorylation as well as decreased levels of cyclinD1 and c-myc proteins. We further showed that Wnt/β-catenin activator reversed the effects of KLK4 silencing on the proliferation and apoptosis of OSCC cells. We concluded that KLK4 silencing inhibited the growth of OSCC cells through Wnt/β-catenin signaling pathway, suggesting that KLK4 may become a promising therapeutic target for the treatment of OSCC.

Dickkopf-related protein 3 negatively regulates the osteogenic differentiation of rat dental follicle cells

The present study aimed to investigate the effect of Dickkopf-related protein 3 (DKK3) on osteogenic differentiation of rat dental follicle cells (DFCs). A PCR array analysis of Wnt pathway activation in DFCs identified genes dysregulated by mineral induction. Among them, DKK3expression levels were decreased, and further experiments were conducted to investigate its role in DFC osteogenesis. By comparing DFCs grown in normal growth and mineral-induction media for 4 weeks, the present study confirmed that DKK3 was a potential target gene of osteogenesis through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB). A short hairpin RNA (shRNA) was introduced into DFCs using a lentiviral vector to inhibit DKK3 expression. An alkaline phosphatase (ALP) activity assay and Alizarin Red staining were performed to observe the DKK3-shRNA DFCs. In addition, the osteogenic differentiation of DKK3-shRNA DFCs was analyzed by RT-qPCR and WB. In vivo, DKK3-shRNA DFCs seeded on hydroxyapatite/β-tricalcium phosphate (HA/TCP) scaffolds were transplanted into the subcutaneous tissue of mice with severe combined immunodeficiency, followed by hematoxylin-eosin and Masson staining. The results confirmed that DKK3 expression was downregulated during mineral induction in rat DFCs. Lentivirus-mediated expression of DKK3 shRNA in DFCs promoted calcified-nodule formation, ALP activity and the expression of β-catenin, runt-related transcription factor 2 and osteocalcin, compared with control cells. In vivo, the implanted section presented the majority of newly formed osteoid matrices and collagen, with limited space between the HA/TCP scaffolds and matrices. In conclusion, DKK3 expression negatively regulates the osteogenic differentiation of DFCs and, conversely, downregulation of DKK3 may enhance DFC osteogenesis.

Immunoexpression of Wnt/β-catenin signaling pathway proteins in ameloblastoma and calcifying cystic odontogenic tumor

Background

Wnt/β-catenin signaling pathway is essential for the beginning of odontogenesis and may be involved in the development and progression of some odontogenic tumors. Thus, the aim of this study was to comparatively evaluate the immunohistochemical expression of Wnt/β-catenin signaling pathway proteins in a series of AME and CCOT.

Material and Methods

Immunohistochemical reactions were performed using antibodies against Wnt1, Wnt5a and β-catenin in 17 cases of solid AME and 6 cases of CCOT.

Results

In the AME group, Wnt1 and Wnt5a were identified in the epithelium in most of the cases, and β-catenin was mainly identified in the cytoplasm of the tumoral cells. In the CCOT group, Wnt1 and Wnt5a were identified in the epithelium and in the ghost cells in almost all the cases, and β-catenin was mainly identified in the cytoplasm and in the nuclei of the tumoral cells.

Conclusions

These results contribute to support the importance of Wnt/β-catenin signaling pathway proteins in AME and CCOT tumorigenesis. The abnormal expression of cytoplasmic and/or nuclear β-catenin appears to contribute to the development of both AME and CCOT. In addition, it is possible that Wnt1 and Wnt5a expression in ghost cells can contribute to its histogenesis in CCOT.

Key words:Ameloblastoma, β-catenin, calcifying cystic odontogenic tumor, immunohistochemistry, Wnt.

Abnormal primary and permanent dentitions with ectodermal symptoms predict WNT10A deficiency

BACKGROUND

The WNT10A protein is critical for the development of ectodermal appendages. Variants in the WNT10A gene may be associated with a spectrum of ectodermal abnormalities including extensive tooth agenesis.

METHODS

In seven patients with severe tooth agenesis we identified anomalies in primary dentition and additional ectodermal symptoms, and assessed WNT10A mutations by genetic analysis.

RESULTS

Investigation of primary dentition revealed peg-shaped crowns of primary mandibular incisors and three individuals had agenesis of at least two primary teeth. The permanent dentition was severely affected in all individuals with a mean of 21 missing teeth. Primary teeth were most often present in positions were succedaneous teeth were missing. Furthermore, most existing molars had taurodontism. Light, brittle or coarse hair was reported in all seven individuals, hyperhidrosis of palms and soles in six individuals and nail anomalies in two individuals. The anomalies in primary dentition preceded most of the additional ectodermal symptoms. Genetic analysis revealed that all seven individuals were homozygous or compound heterozygous for WNT10A mutations resulting in C107X, E222X and F228I.

CONCLUSIONS

We conclude that tooth agenesis and/or peg-shaped crowns of primary mandibular incisors, severe oligodontia of permanent dentition as well as ectodermal symptoms of varying severity may be predictors of bi-allelic WNT10A mutations of importance for diagnosis, counselling and follow-up.