Wnt/ß-catenin-C-kit axis may play a role in adenoid cystic carcinoma prognostication.

Adenoid cystic carcinoma (ACC) is one of the most common malignant salivary gland tumors. ACC is composed of myoepithelial and epithelial neoplastic cells which grow slowly and have a tendency for neural invasion. The long term prognosis is still relatively poor. Although several gene abnormalities, such as fusions involving MYB or MYBL1 oncogenes and the transcription factor gene NFIB, and overexpression of KIT have been reported in ACC, their precise functions in the pathogenesis of ACC remain unclear. We recently demonstrated that the elevated expression of Semaphorin 3A (SEMA3A), specifically expressed in myoepithelial neoplastic cells, might function as a novel oncogene-related molecule to enhance cell proliferation through activated AKT signaling in 9/10 (90%) ACC cases. In the current study, the patient with ACC whose tumor was negative for SEMA3A in the previous study, revisited our hospital with late metastasis of ACC to the cervical lymph node eight years after surgical resection of the primary tumor. We characterized this recurrent ACC, and compared it with the primary ACC using immunohistochemical methods. In the recurrent ACC, the duct lining epithelial cells, not myoepithelial neoplastic cells, showed an elevated Ki-67 index and increased cell membrane expression of C-kit, along with the expression of phosphorylated ERK. Late metastasis ACC specimens were not positive for ß-catenin and lymphocyte enhancer binding factor 1 (LEF1), which were detected in the nuclei of perineural infiltrating cells in primary ACC cells. In addition, experiments with the GSK-3 inhibitor revealed that ß-catenin pathway suppressed not only KIT expression but also proliferation of ACC cells. Moreover, stem cell factor (SCF; also known as KIT ligand, KITL) induced ERK activation in ACC cells. These results suggest that inactivation of Wnt/ß-catenin signaling may promote C-kit-ERK signaling and cell proliferation of in metastatic ACC.

The IL-1ß-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-ß signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation.

AIM: Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-ß signalling and IL-1ß signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines. METHODOLOGY: Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-ß1 and IL-1ß. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined. RESULTS: Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-ß1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-ß1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1ß stimulation reversed these phenotypes through p65 transactivation. CONCLUSIONS: These results suggest that IL-1ß-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-ß-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

Expansion of CD4+ cytotoxic T lymphocytes with specific gene expression patterns may contribute to suppression of tumor immunity in oral squamous cell carcinoma: single-cell analysis and in vitro experiments.

Background: Cancer immunotherapy targeting CD8+ T cells has made remarkable progress, even for oral squamous cell carcinoma (OSCC), a heterogeneous epithelial tumor without a substantial increase in the overall survival rate over the past decade. However, the therapeutic effects remain limited due to therapy resistance. Thus, a more comprehensive understanding of the roles of CD4+ T cells and B cells is crucial for more robust development of cancer immunotherapy. Methods: In this study, we examined immune responses and effector functions of CD4+ T cells, CD8+ T cells and B cells infiltrating in OSCC lesions using single-cell RNA sequencing analysis, T cell receptor (TCR) and B cell receptor (BCR) repertoire sequencing analysis, and multi-color immunofluorescence staining. Finally, two Kaplan-Meier curves and several Cox proportional hazards models were constructed for the survival analysis. Results: We observed expansion of CD4+ cytotoxic T lymphocytes (CTLs) expressing granzymes, which are reported to induce cell apoptosis, with a unique gene expression patterns. CD4+ CTLs also expressed CXCL13, which is a B cell chemoattractant. Cell-cell communication analysis and multi-color immunofluorescence staining demonstrated potential interactions between CD4+ CTLs and B cells, particularly IgD- CD27- double negative (DN) B cells. Expansion of CD4+ CTLs, DN B cells, and their contacts has been reported in T and B cell-activated diseases, including IgG4-related disease and COVID-19. Notably, we observed upregulation of several inhibitory receptor genes including CTLA-4 in CD4+ CTLs, which possibly dampened T and B cell activity. We next demonstrated comprehensive delineation of the potential for CD8+ T cell differentiation towards dysfunctional states. Furthermore, prognostic analysis revealed unfavorable outcomes of patients with a high proportion of CD4+ CTLs in OSCC lesions. Conclusion: Our study provides a dynamic landscape of lymphocytes and demonstrates a systemic investigation of CD4+ CTL effects infiltrating into OSCC lesions, which may share some pathogenesis reported in severe T and B cell-activated diseases such as autoimmune and infectious diseases.

Arl4c is involved in tooth germ development through osteoblastic/ameloblastic differentiation.

Murine tooth germ development proceeds in continuous sequential steps with reciprocal interactions between the odontogenic epithelium and the adjacent mesenchyme, and several growth factor signaling pathways and their activation are required for tooth germ development. The expression of ADP-ribosylation factor (Arf)-like 4c (Arl4c) has been shown to induce cell proliferation, and is thereby involved in epithelial morphogenesis and tumorigenesis. In contrast, the other functions of Arl4c (in addition to cellular growth) are largely unknown. Although we recently demonstrated the involvement of the upregulated expression of Arl4c in the proliferation of ameloblastomas, which have the same origin as odontogenic epithelium, its effect on tooth germ development remains unclear. In the present study, single-cell RNA sequencing (scRNA-seq) analysis revealed that the expression of Arl4c, among 17 members of the Arf-family, was specifically detected in odontogenic epithelial cells, such as those of the stratum intermedium, stellate reticulum and outer enamel epithelium, of postnatal day 1 (P1) mouse molars. scRNA-seq analysis also demonstrated the higher expression of Arl4c in non-ameloblast and inner enamel epithelium, which include immature cells, of P7 mouse incisors. In the mouse tooth germ rudiment culture, treatment with SecinH3 (an inhibitor of the ARNO/Arf6 pathway) reduced the size, width and cusp height of the tooth germ and the thickness of the eosinophilic layer, which would involve the synthesis of dentin and enamel matrix organization. In addition, loss-of-function experiments using siRNAs and shRNA revealed that the expression of Arl4c was involved in cell proliferation and osteoblastic cytodifferentiation in odontogenic epithelial cells. Finally, RNA-seq analysis with a gene set enrichment analysis (GSEA) and Gene Ontology (GO) analysis showed that osteoblastic differentiation-related gene sets and/or GO terms were downregulated in shArl4c-expressing odontogenic epithelial cells. These results suggest that the Arl4c-ARNO/Arf6 pathway axis contributes to tooth germ development through osteoblastic/ameloblastic differentiation.

Stepwise activation of p63 and the MEK/ERK pathway induces the expression of ARL4C to promote oral squamous cell carcinoma cell proliferation.

Carcinogenesis is a multistep process wherein cells accumulate multiple genetic alterations and progress to a more malignant phenotype. It has been proposed that sequential accumulation of gene abnormalities in specific genes drives the transition from non-tumorous epithelia through a preneoplastic lesion/benign tumor to cancer. Histologically, oral squamous cell carcinoma (OSCC) progresses in multiple ordered steps that begin with mucosal epithelial cell hyperplasia, which is followed by dysplasia, carcinoma in situ and invasive carcinoma. It is therefore hypothesized that genetic alteration-mediated multistep carcinogenesis would be involved in the development of OSCC; however, the detailed molecular mechanisms are unknown. We clarified the comprehensive gene expression patterns and carried out an enrichment analysis using DNA microarray data from a pathological specimen of OSCC (including a non-tumor region, carcinoma in situ lesion and invasive carcinoma lesion). The expression of numerous genes and signal activation were altered in the development of OSCC. Among these, the p63 expression was increased and the MEK/ERK-MAPK pathway was activated in carcinoma in situ lesion and in invasive carcinoma lesion. Immunohistochemical analyses revealed that p63 was initially upregulated in carcinoma in situ and ERK was sequentially activated in invasive carcinoma lesions in OSCC specimens. ADP-ribosylation factor (ARF)-like 4c (ARL4C), the expression of which is reportedly induced by p63 and/or the MEK/ERK-MAPK pathway in OSCC cells, has been shown to promote tumorigenesis. Immunohistochemically, in OSCC specimens, ARL4C was more frequently detected in tumor lesions, especially in invasive carcinoma lesions, than in carcinoma in situ lesions. Additionally, ARL4C and phosphorylated ERK were frequently merged in invasive carcinoma lesions. Loss-of-function experiments using inhibitors and siRNAs revealed that p63 and MEK/ERK-MAPK cooperatively induce the expression of ARL4C and cell growth in OSCC cells. These results suggest that the stepwise activation of p63 and MEK/ERK-MAPK contributes to OSCC tumor cell growth through regulation of ARL4C expression.

Dopamine is involved in reparative dentin formation through odontoblastic differentiation of dental pulp stem cells.

Conventional direct pulp-capping materials induce pulp cells to secrete various biomolecules in pulp tissues that promote reparative dentin formation through induction of odontoblastic differentiation of dental pulp stem cells (DPSCs). However, these biomolecules sometimes induce bone-like dentin with poor sealing properties. Therefore, exploration of biomolecules that allow tight sealing by tubular reparative dentin is required. We recently reported that dopamine (DA) is involved in dentinogenesis. Hence, we investigated the effect of DA on odontoblastic differentiation of DPSCs and reparative dentin formation. Both tyrosine hydroxylase (TH), a DA synthetase, and DA were expressed in odontoblast-like cells in vivo. In vitro, their expression was increased during odontoblastic differentiation of DPSCs. Furthermore, TH-overexpressing DPSCs had promoted odontoblastic differentiation and DA production. Moreover, DA stimulation promoted their differentiation and induced tubular reparative dentin. These results suggest that DA produced by TH is involved in odontoblastic differentiation of DPSCs and has an inductive capacity for reparative dentin formation similar to primary dentin. This study may lead to the development of therapy to preserve vital pulp tissues.

The role of Wnt, ARL4C, and Sema3A in developmental process and disease pathogenesis.

Various types of tumors, including malignant and benign ones, occur in the oral cavity. These arise from the mucosal epithelium, odontogenic epithelium, and salivary gland. To date, few major driver events in oral tumors have been identified. Accordingly, molecular targets in anti-tumor therapy for oral tumors are lacking. We focused on elucidating the function of aberrantly activated signal transduction related to oral tumor formation, especially in oral squamous cell carcinoma, ameloblastoma, and adenoid cystic carcinoma, which are raised as common oral tumors. Wnt/ß-catenin-dependent pathway is involved in the developmental process, organ homeostasis and disease pathogenesis through regulating various cellular functions by enhancing transcriptional activity. Recently, we identified ADP-ribosylation factor (ARF)-like 4c (ARL4C) and Semaphorin 3A (Sema3A), the expression of which is regulated by Wnt/ß-catenin-dependent pathway, and characterized their functions in the developmental process and tumor formation. This review highlights the recent advances in understanding the roles of Wnt/ß-catenin-dependent pathway, ARL4C and Sema3A, as determined by pathological and experimental studies.

RNA Taste Is Conserved in Dipteran Insects.

BACKGROUND: Ribonucleosides and RNA are an underappreciated nutrient group essential during Drosophila larval development and growth. Detection of these nutrients requires at least one of the 6 closely related taste receptors encoded by the Gr28 genes, one of the most conserved insect taste receptor subfamilies. OBJECTIVES: We investigated whether blow fly larvae and mosquito larvae, which shared the last ancestor with Drosophila about 65 and 260 million years ago, respectively, can taste RNA and ribose. We also tested whether the Gr28 homologous genes of the mosquitoes Aedes aegypti and Anopheles gambiae can sense these nutrients when expressed in transgenic Drosophila larvae. METHODS: Taste preference in blow flies was examined by adapting a 2-choice preference assay that has been well-established for Drosophila larvae. For the mosquito Aedes aegypti, we developed a new 2-choice preference assay that accommodates the aquatic environment of these insect larvae. Finally, we identified Gr28 homologs in these species and expressed them in Drosophila melanogaster to determine their potential function as RNA receptors. RESULTS: Larvae of the blow fly Cochliomyia macellaria and Lucilia cuprina are strongly attracted to RNA (0.5 mg/mL) in the 2-choice feeding assays (P < 0.05). Similarly, the mosquito Aedes aegypti larvae showed a strong preference for RNA (2.5 mg/mL) in an aquatic 2-choice feeding assay. Moreover, when Gr28 homologs of Aedes or Anopheles mosquitoes are expressed in appetitive taste neurons of Drosophila melanogaster larvae lacking their Gr28 genes, preference for RNA (0.5 mg/mL) and ribose (0.1 M) is rescued (P < 0.05). CONCLUSIONS: The appetitive taste for RNA and ribonucleosides in insects emerged about 260 million years ago, the time mosquitoes and fruit flies diverged from their last common ancestor. Like sugar receptors, receptors for RNA have been highly conserved during insect evolution, suggesting that RNA is a critical nutrient for fast-growing insect larvae.

p130Cas is required for androgen-dependent postnatal development regulation of submandibular glands.

Salivary glands develop through epithelial-mesenchymal interactions and are formed through repeated branching. The Crk-associated substrate protein (p130Cas) serves as an adapter that forms a complex with various proteins via integrin and growth factor signaling, with important regulatory roles in several essential cellular processes. We found that p130Cas is expressed in ductal epithelial cells of the submandibular gland (SMG). We generated epithelial tissue-specific p130Cas-deficient (p130CasΔepi-) mice and aimed to investigate the physiological role of p130Cas in the postnatal development of salivary glands. Histological analysis showed immature development of granular convoluted tubules (GCT) of the SMG in male p130CasΔepi- mice. Immunofluorescence staining showed that nuclear-localized androgen receptors (AR) were specifically decreased in GCT cells in p130CasΔepi- mice. Furthermore, epidermal growth factor-positive secretory granules contained in GCT cells were significantly reduced in p130CasΔepi- mice with downregulated AR signaling. GCTs lacking p130Cas showed reduced numbers and size of secretory granules, disrupted subcellular localization of the cis-Golgi matrix protein GM130, and sparse endoplasmic reticulum membranes in GCT cells. These results suggest that p130Cas plays a crucial role in androgen-dependent GCT development accompanied with ER-Golgi network formation in SMG by regulating the AR signaling.

Usefulness of reconstructed images of Gd-enhanced 3D gradient echo sequences with compressed sensing for mandibular cancer diagnosis: comparison with CT images and histopathological findings.

OBJECTIVES: To compare the delineation of mandibular cancer by 3D T1 turbo field echo with compressed SENSE (CS-3D-T1TFE) images and MDCT images, and to compare both sets of images with histopathological findings, as the gold standard, to validate the accuracy and clinical usefulness of CS-3D-T1TFE reconstruction. METHODS: Twenty-four patients with mandibular squamous cell carcinoma (SCC) who underwent MRI including CS-3D-T1TFE and MDCT examinations before surgery were retrospectively included. For both examinations, 0.5-mm-thick coronal plane images and 0.5-mm-thick plane images perpendicular and parallel to the dentition were constructed. Two radiologists rated bone invasion in three categories indexed by cortical bone, cancellous bone, and mandibular canal (MC), and inter-rater agreement was assessed by weighted kappa statistics. In 20 of the 24 patients who underwent surgery, the correlation of bone invasion with the histopathological evaluation by pathologists was assessed using Pearson's correlation coefficient. Soft-tissue invasion was assessed by diagnosing the presence of invasion into the mylohyoid muscle, gingivobuccal fold, and masticator space, and inter-rater agreement was assessed by kappa statistics. RESULTS: The interobserver agreement for bone invasion assessment was almost perfect with CS-3D-T1TFE and substantial with MDCT. The image evaluations by both observers agreed with the pathological evaluations in 15 of the 20 cases, showing high correlation (r > 0.8). CS-3D-T1TFE also showed higher inter-rater agreement than MDCT for all measures of soft-tissue invasion. CONCLUSIONS: CS-3D-T1TFE reconstructed images were clinically useful in accurately depicting the extent of mandibular cancer invasion and potentially solving the problem of lesion overestimation associated with conventional MRI. KEY POINTS: • Reconstructed CS-3D-T1TFE images were useful for the diagnosis of mandibular cancer. • CS-3D-T1TFE images showed higher inter-rater agreement than MDCT and high correlation with pathological findings. • CS-3D-T1TFE images may solve the problem of overestimation of the tumor extent, which has been associated with MRI in the past.

Lipomatous mixed tumor of the skin with cystic formation affecting the upper lip: A case report.

Mixed tumor of the skin (MTS) is a rare neoplasm derived from the sweat glands with a reported frequency of 0.01-0.098% among all primary skin tumors. MTS often occurs in the head and neck region and is characterized by a mixture of epithelial, myoepithelial and stromal components. MTS also shows various morphological patterns, thus the presence of variants with rare components and its rarity make the clinical diagnosis even more difficult. A 47-year-old man was referred due to a painless, slowly growing, exophytic swelling intracutaneous mass of the upper lip. Magnetic resonance imaging revealed that the mass was a solid tumor with a fatty component in the proximal portion, while the distal portion was cystic and possibly contained highly viscous fluid. The mass was located between the skin and the orbicularis oris muscle in the upper lip. Excisional biopsy was performed and the lesion showed two intriguing features: A tumor with extensive lipomatous stroma and some large cysts. It was histopathologically diagnosed as lipomatous MTS with cystic formation in the upper lip. No evident signs of recurrence were observed during follow-up. The present report describes this case and includes a brief literature review of reported cases in the lip, since MTS can be confused with various skin lesions in clinical settings due to this rarity. Recognition by clinicians of different variants of MTSs, including the present case, is important for preventing erroneous diagnosis and treatment.

Wnt signaling promotes tooth germ development through YAP1-TGF-ß signaling.

Tooth germ development involves continuous and sequential steps with reciprocal interactions between odontogenic epithelium and the adjacent mesenchyme. Several growth factors, including Wnt, are essential for tooth germ development. Molecular mechanisms underlying Wnt/ß-catenin-regulated tooth germ development are poorly understood. In tooth germ rudiments culture, we recently demonstrated that Semaphorin 3A (Sema3A), an axonal guidance factor, stimulation reversed Wnt/ß-catenin signaling-dependent decreased cell proliferation but did not completely rescue the morphological anomalies of tooth germ, suggesting that an uncharacterized signaling pathway may be essential in Wnt/ß-catenin signaling-dependent tooth germ development. Herein, an enrichment analysis using DNA microarray data, which was obtained in our previous research, revealed that Wnt/ß-catenin signaling negatively regulates YAP1 and/or TGF-ß signalings. In odontogenic epithelial cells and tooth germ rudiments, Wnt/ß-catenin signaling activation reduced YAP1 expression, thereby suppressing YAP1 and TGF-ß signalings sequentially. Additionally, YAP1 signaling induced TGF-ß2 expression to promote TGF-ß signaling in the cells. Finally, Wnt/ß-catenin signaling-dependent disorganized tooth germ development, in which YAP1 signaling was suppressed, was reversed by TGF-ß stimulation. These results suggest that Wnt/ß-catenin signaling contributes to the tooth germ development through YAP1-TGF-ß signaling.

The Semaphorin 3A-AKT axis-mediated cell proliferation in salivary gland morphogenesis and adenoid cystic carcinoma pathogenesis.

We recently demonstrated that Semaphorin 3 A (Sema3A), the expression of which is negatively regulated by Wnt/ß-catenin signaling, promotes odontogenic epithelial cell proliferation, suggesting the involvement of Sema3A in tooth germ development. Salivary glands have a similar developmental process to tooth germ development, in which reciprocal interactions between the oral epithelium and adjacent mesenchyme proceeds via stimulation with several growth factors; however, the role of Sema3A in the development of salivary glands is unknown. There may thus be a common mechanism between epithelial morphogenesis and pathogenesis; however, the role of Sema3A in salivary gland tumors is also unclear. The current study investigated the involvement of Sema3A in submandibular gland (SMG) development and its expression in adenoid cystic carcinoma (ACC) specimens. Quantitative RT-PCR and immunohistochemical analyses revealed that Sema3A was expressed both in epithelium and in mesenchyme in the initial developmental stages of SMG and their expressions were decreased during the developmental processes. Loss-of-function experiments using an inhibitor revealed that Sema3A was required for AKT activation-mediated cellular growth and formation of cleft and bud in SMG rudiment culture. In addition, Wnt/ß-catenin signaling decreased the Sema3A expression in the rudiment culture. ACC arising from salivary glands frequently exhibits malignant potential. Immunohistochemical analyses of tissue specimens obtained from 10 ACC patients showed that Sema3A was hardly observed in non-tumor regions but was strongly expressed in tumor lesions, especially in myoepithelial neoplastic cells, at high frequencies where phosphorylated AKT expression was frequently detected. These results suggest that the Sema3A-AKT axis promotes cell growth, thereby contributing to morphogenesis and pathogenesis, at least in ACC, of salivary glands.

Clear cell squamous cell carcinoma of the tongue exhibits characteristics as an undifferentiated squamous cell carcinoma.

Clear cell squamous cell carcinoma (CCSCC), where cells show abundant clear cytoplasm, -is a variant of squamous cell carcinoma (SCC) and a rare entity in the oral cavity. The characteristics of CCSCC, especially in immunohistochemical features, remain unclear. We characterized a case of CCSCC arising from the oral mucosal epithelium of tongue, where the clear cell lesion accounted for a predominant portion of the tumor. This CCSCC, which was partially surrounded by conventional SCC, exhibited cellular atypia immunohistopathologically and histopathologically with a high Ki-67 index, increased number of mitotic figures and enlarged nuclei. Intravascular invasion of the carcinoma cells was also observed. Furthermore, the CCSCC recurred and metastasized to the cervical lymph nodes and both lungs three months after resection. Immunohistochemical analyses demonstrated decreased expression of p40 (an isoform of SCC marker p63), ADP-ribosylation factor (ARF)-like 4c (ARL4C), yes-associated protein (YAP) and 5-methylcytosine (5mC) in the CCSCC lesion compared with the surrounding SCC lesion, where the expression of ARL4C was upregulated compared with non-tumor region and YAP showed nuclear translocation. In addition, siRNA loss-of-function experiments revealed that p63 expression was required for ARL4C expression and DNA methylation was induced by p63 and YAP/transcriptional co-activator with PDZ-binding motif (TAZ) signaling in oral SCC cell lines. These results suggest that CCSCC, in which several markers of SCC-associated intracellular signaling pathways are downregulated, together with evidence of altered epigenetic regulation, is characterized as an undifferentiated SCC variant.

RAF1-MEK/ERK pathway-dependent ARL4C expression promotes ameloblastoma cell proliferation and osteoclast formation.

Ameloblastoma is an odontogenic neoplasm characterized by slow intraosseous growth with progressive jaw resorption. Recent reports have revealed that ameloblastoma harbours an oncogenic BRAFV600E mutation with mitogen-activated protein kinase (MAPK) pathway activation and described cases of ameloblastoma harbouring a BRAFV600E mutation in which patients were successfully treated with a BRAF inhibitor. Therefore, the MAPK pathway may be involved in the development of ameloblastoma; however, the precise mechanism by which it induces ameloblastoma is unclear. The expression of ADP-ribosylation factor (ARF)-like 4c (ARL4C), induced by a combination of the EGF-MAPK pathway and Wnt/ß-catenin signalling, has been shown to induce epithelial morphogenesis. It was also reported that the overexpression of ARL4C, due to alterations in the EGF/RAS-MAPK pathway and Wnt/ß-catenin signalling, promotes tumourigenesis. However, the roles of ARL4C in ameloblastoma are unknown. We investigated the involvement of ARL4C in the development of ameloblastoma. In immunohistochemical analyses of tissue specimens obtained from 38 ameloblastoma patients, ARL4C was hardly detected in non-tumour regions but tumours frequently showed strong expression of ARL4C, along with the expression of both BRAFV600E and RAF1 (also known as C-RAF). Loss-of-function experiments using inhibitors or siRNAs revealed that ARL4C elevation depended on the RAF1-MEK/ERK pathway in ameloblastoma cells. It was also shown that the RAF1-ARL4C and BRAFV600E-MEK/ERK pathways promoted cell proliferation independently. ARL4C-depleted tumour cells (generated by knockdown or knockout) exhibited decreased proliferation and migration capabilities. Finally, when ameloblastoma cells were co-cultured with mouse bone marrow cells and primary osteoblasts, ameloblastoma cells induced osteoclast formation. ARL4C elevation in ameloblastoma further promoted its formation capabilities through the increased RANKL expression of mouse bone marrow cells and/or primary osteoblasts. These results suggest that the RAF1-MEK/ERK-ARL4C axis, which may function in cooperation with the BRAFV600E-MEK/ERK pathway, promotes ameloblastoma development. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Bone morphogenetic protein induces bone invasion of melanoma by epithelial-mesenchymal transition via the Smad1/5 signaling pathway.

Oral malignant melanoma, which frequently invades the hard palate or maxillary bone, is extremely rare and has a poor prognosis. Bone morphogenetic protein (BMP) is abundantly expressed in bone matrix and is highly expressed in malignant melanoma, inducing an aggressive phenotype. We examined the role of BMP signaling in the acquisition of an aggressive phenotype in melanoma cells in vitro and in vivo. In five cases, immunohistochemistry indicated the phosphorylation of Smad1/5 (p-Smad1/5) in the nuclei of melanoma cells. In the B16 mouse and A2058 human melanoma cell lines, BMP2, BMP4, or BMP7 induces morphological changes accompanied by the downregulation of E-cadherin, and the upregulation of N-cadherin and Snail, markers of epithelial-mesenchymal transition (EMT). BMP2 also stimulates cell invasion by increasing matrix metalloproteinase activity in B16 cells. These effects were canceled by the addition of LDN193189, a specific inhibitor of Smad1/5 signaling. In vivo, the injection of B16 cells expressing constitutively activated ALK3 enhanced zygoma destruction in comparison to empty B16 cells by increasing osteoclast numbers. These results suggest that the activation of BMP signaling induces EMT, thus driving the acquisition of an aggressive phenotype in malignant melanoma.

Tumor contact length of prostate cancer determined by a three-dimensional method on multiparametric magnetic resonance imaging predicts extraprostatic extension and biochemical recurrence.

OBJECTIVE: To evaluate the clinical benefit of tumor contact length as a predictor of pathological extraprostatic extension and biochemical recurrence in patients undergoing prostatectomy. METHODS: A total of 91 patients who underwent 3T multiparametric magnetic resonance imaging before prostatectomy from April 2014 to July 2019 were included. A total of 94 prostate cancer foci were analyzed retrospectively. We evaluated maximum tumor contact length, which was determined to be the maximum value in the three-dimensional directions, as a predictor of pathological extraprostatic extension and biochemical recurrence. RESULTS: A total of 19 lesions (20.2%) had positive pathological extraprostatic extension. Areas under the curves showed maximum tumor contact length to be a significantly better parameter to predict pathological extraprostatic extension than the Prostate Imaging Reporting and Data System (P = 0.002), tumor maximal diameter (P = 0.001), prostate-specific antigen (P = 0.020), Gleason score (P < 0.001), and clinical T stage (P < 0.001). Multivariate analysis showed maximum tumor contact length (P = 0.003) to be an independent risk factor for predicting biochemical recurrence. We classified the patients using preoperative factors (prostate-specific antigen >10, Gleason score >3 + 4 and maximum tumor contact length >10 mm) into three groups: (i) high-risk group (patients having all factors); (ii) intermediate-risk group (patients having two of three factors); and (iii) low-risk group (patients having only one or none of the factors). Kaplan-Meier curves showed that the high-risk group had significantly worse biochemical recurrence than the intermediate-risk group (P = 0.042) and low-risk group (P < 0.001). CONCLUSIONS: Our findings suggest that maximum tumor contact length is an independent predictor of pathological extraprostatic extension and biochemical recurrence. A risk stratification system using prostate-specific antigen, Gleason score and maximum tumor contact length might be useful for preoperative assessment of prostate cancer patients.

YAP signaling induces PIEZO1 to promote oral squamous cell carcinoma cell proliferation.

Most cancer cells are exposed to altered extracellular environments, such as an increase in extracellular matrix (ECM) stiffness and soluble signals consisting of growth factors and cytokines. It is therefore conceivable that changes in tumor extracellular environments affect tumor cell behavior. The Hippo pathway reportedly responds to the extracellular environment and regulates the nuclear localization of the transcription co-activator, yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ). Inactivation of the Hippo pathway with nuclear translocation of YAP/TAZ stimulates cell proliferation. Its pathway also regulates gene expression, but the precise molecule(s) meditating the cell-proliferating effect of YAP signaling on oral squamous cell carcinoma (OSCC) is unclear. First, we examined the effects of YAP signaling on OSCC tumorigenesis. Loss-of-function experiments using siRNA or an inhibitor, and immunohistochemical analyses of tissue specimens obtained from OSCC patients demonstrated that YAP signaling was involved in OSCC cell proliferation. Second, we identified Piezo-type mechanosensitive ion channel component 1 (PIEZO1), a Ca2+ channel, as a transcriptional target of YAP signaling and showed that elevated PIEZO1 was required for PIEZO1 agonist-dependent Ca2+ entry and cell proliferation in OSCC cells. Experiments using three-dimensional and suspension culture revealed that PIEZO1 was involved in OSCC cellular growth. Finally, YAP overexpression in the nucleus and/or cytoplasm was immunohistochemically detected in tumor lesions with frequent expression of both PIEZO1 and Ki-67, but not in non-tumor regions of OSCC specimens. These results suggest that the YAP/PIEZO1 axis promotes OSCC cell growth. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Refractory fistula of bladder repaired with transurethral cystoscopic injection of N-butyl-2-cyanoacrylate.

INTRODUCTION: Refractory fistulas of the bladder are not rare, but they can rarely be closed naturally. Bladder fistulas can be treated in various ways. We report the case of an old woman who had a refractory fistula of the bladder that was able to be repaired with transurethral cystoscopic injection of N-butyl-2-cyanoacrylate. CASE PRESENTATION: For decades after being treated for cervical cancer in 1970s, the woman frequently suffered from fevers. A computed tomography scan showed pelvic abscess at the left side of her bladder, and cystography showed urine leakage at the wall. Thus, we diagnosed her with a pelvic abscess due to a bladder fistula after radiation. Then, we treated her with drainage, antibiotic agents, and N-butyl-2-cyanoacrylate. After that, she no longer had fevers, and cystography showed no leakage of urine. CONCLUSION: This result indicates transurethral cystoscopic injection of N-butyl-2-cyanoacrylate may treat bladder fistulas safely, minimally invasively, and quickly.

The TRPV4-AKT axis promotes oral squamous cell carcinoma cell proliferation via CaMKII activation.

Most human malignant tumor cells arise from epithelial tissues, which show distinctive characteristics, such as polarization, cell-to-cell contact between neighboring cells, and anchoring to a basement membrane. When tumor cells invaginate into the stroma, the cells are exposed to extracellular environments, including the extracellular matrix (ECM). Increased ECM stiffness has been reported to promote cellular biological activities, such as excessive cellular growth and enhanced migration capability. Therefore, tumorous ECM stiffness is not only an important clinical tumor feature but also plays a pivotal role in tumor cell behavior. Transient receptor potential vanilloid 4 (TRPV4), a Ca2+-permeable nonselective cation channel, has been reported to be mechano-sensitive and to regulate tumorigenesis, but the underlying molecular mechanism in tumorigenesis remains unclear. The function of TRPV4 in oral squamous cell carcinoma (OSCC) is also unknown. The current study was conducted to investigate whether or not TRPV4 might be involved in OSCC tumorigenesis. TRPV4 mRNA levels were elevated in OSCC cell lines compared with normal oral epithelial cells, and its expression was required for TRPV4 agonist-dependent Ca2+ entry. TRPV4-depleted tumor cells exhibited decreased proliferation capabilities in three-dimensional culture but not in a low-attachment plastic dish. A xenograft tumor model demonstrated that TRPV4 expression was involved in cancer cell proliferation in vivo. Furthermore, loss-of-function experiments using siRNA or an inhibitor revealed that the TRPV4 expression was required for CaMKII-mediated AKT activation. Immunohistochemical analyses of tissue specimens obtained from 36 OSCC patients showed that TRPV4 was weakly observed in non-tumor regions but was strongly expressed in tumor lesions at high frequencies where phosphorylated AKT expression was frequently detected. These results suggest that the TRPV4/CaMKII/AKT axis, which might be activated by extracellular environments, promotes OSCC tumor cell growth.