Hypoxia enhances basal autophagy of epithelial-derived ameloblastoma cells.

Ameloblastoma is a locally aggressive odontogenic tumor. Etiopathogenesis and locally aggressive growth properties of ameloblastoma can be attributed to a hypoxic microenvironment conducive to tumor cell survival. Epithelial-derived follicular ameloblastoma cells (EP-AMCs) display enhanced basal autophagy, but the interplay of hypoxia and autophagy in EP-AMCs survival and ameloblastoma recurrence is unclear. We evaluated differential expression of autophagic markers in primary and recurrent ameloblastomas and hypothesized that hypoxia-induced autophagy supports EP-AMC survival. Primary and recurrent ameloblastomas were comparatively assessed for expression levels of pan-cytokeratin, Vimentin, and autophagic markers SQSTM1/p62, LC3, and pS6. EP-AMCs compared with human odontoma-derived cells (HODCs) were subjected to severe hypoxia to determine the interplay of hypoxia and autophagic process in posthypoxia survival. Pan-cytokeratin and SQSTM1/p62 were expressed by both primary and recurrent ameloblastoma epithelial cells while the ameloblastoma connective tissues displayed weak reactivity to vimentin. Under hypoxia, EP-AMC expression levels of hypoxia-inducible factor (HIF)-1α, p62, and LC3 were increased while pS6 was decreased posthypoxia. The combined decrease in pS6 and enhanced LC3 in EP-AMCs under hypoxia indicate that EP-AMCs re-establish basal autophagy under hypoxia. Taken together, these suggest a possible role of LC3-associated phagocytosis (LAP) in ameloblastoma cell survival.

Unusual oral multifocal epithelial hyperplasia in an adult African-American lung transplant patient.

Oral multifocal epithelial hyperplasia (MEH), or Heck's disease, is a rare benign proliferation of the oral mucosa associated with human papillomavirus (HPV). It clinically presents as multiple asymptomatic papules and nodules that mostly affect the lips, buccal mucosa, and tongue. MEH is predominantly found in children and young adults while relatively few cases have been reported in the elderly population. Here, we report a case of oral MEH in a 65-year-old man with history of lung transplantation. This case highlights the potential susceptibility of organ transplant recipients to the development of MEH. Since MEH that does not require treatment unless the lesion bothers the patient, clinicians should promptly establish a definitive diagnosis to rule out other HPV-related precancerous lesions.

SMARCB1 (Integrase Interactor 1)-Deficient Sinonasal Carcinoma of the Maxillary Sinus: A Newly Described Sinonasal Neoplasm.

SMARCB1 (integrase interactor 1) is a tumor suppressor gene encoded on chromosome 22q11.2 that encodes a core subunit of SWI/SNF chromatin remodeling complexes and plays a critical role in regulating gene expression and chromatin structure. We describe a case of SMARCB1 (integrase interactor 1)-deficient sinonasal carcinoma of the left maxillary sinus in a 63-year-old woman with an initial presentation of numbness of the maxillary teeth and facial swelling.

Mesenchymal Stromal Cell-Derived Interleukin-6 Promotes Epithelial-Mesenchymal Transition and Acquisition of Epithelial Stem-Like Cell Properties in Ameloblastoma Epithelial Cells.

Epithelial-mesenchymal transition (EMT), a biological process associated with cancer stem-like or cancer-initiating cell formation, contributes to the invasiveness, metastasis, drug resistance, and recurrence of the malignant tumors; it remains to be determined whether similar processes contribute to the pathogenesis and progression of ameloblastoma (AM), a benign but locally invasive odontogenic neoplasm. Here, we demonstrated that EMT- and stem cell-related genes were expressed in the epithelial islands of the most common histologic variant subtype, the follicular AM. Our results revealed elevated interleukin (IL)-6 signals that were differentially expressed in the stromal compartment of the follicular AM. To explore the stromal effect on tumor pathogenesis, we isolated and characterized both mesenchymal stromal cells (AM-MSCs) and epithelial cells (AM-EpiCs) from follicular AM and demonstrated that, in in vitro culture, AM-MSCs secreted a significantly higher level of IL-6 as compared to the counterpart AM-EpiCs. Furthermore, both in vitro and in vivo studies revealed that exogenous and AM-MSC-derived IL-6 induced the expression of EMT- and stem cell-related genes in AM-EpiCs, whereas such effects were significantly abrogated either by a specific inhibitor of STAT3 or ERK1/2, or by knockdown of Slug gene expression. These findings suggest that AM-MSC-derived IL-6 promotes tumor-stem like cell formation by inducing EMT process in AM-EpiCs through STAT3 and ERK1/2-mediated signaling pathways, implying a role in the etiology and progression of the benign but locally invasive neoplasm. Stem Cells 2017;35:2083-2094.

Ameloblastic Fibro-Odontoma of the Maxilla in a Pierre-Robin Sequence Patient.

INTRODUCTION: Pierre Robin sequence (PRS) is a rare disorder classically observed as a triad of features including micrognathia, glossoptosis, and upper airway obstruction. It is associated with a syndrome in about 60% of cases. While odontogenic tumors are common findings in patients with familial adenomatous polyposis and nevoid basal cell carcinoma syndromes, PRS has not been found to be consistently associated with any tumors of the jaw. CASE REPORT: The current report aims to describe a patient with PRS who presented with an extensive ameloblastic fibro-odontoma (AFO) of the maxilla. CONCLUSION: Continued observation for odontogenic tumors in PRS is necessary.

Differential requirements for H/ACA ribonucleoprotein components in cell proliferation and response to DNA damage.

H/ACA ribonucleoproteins (RNPs) are comprised of four conserved proteins, dyskerin, NHP2, NOP10, and GAR1, and a function-specifying, noncoding H/ACA RNA. H/ACA RNPs contribute to telomerase assembly and stabilization, and posttranscriptional processing of nascent ribosomal RNA and spliceosomal RNA. However, very little is known about the coordinated action of the four proteins in other biologic processes. As described herein, we observed a differential requirement for the proteins in cell proliferation and identified a possible reliance for these factors in regulation of specific DNA damage biomarkers. In particular, GAR1 expression was upregulated following exposure to all forms of genotoxic stress tested. In contrast, levels of the other proteins were either reduced or unaffected. Only GAR1 showed an altered subcellular localization with a shift from the nucleolus to the nucleoplasm after ultraviolet-C irradiation and doxorubicin treatments. Transient siRNA-mediated depletion of GAR1 and dyskerin arrested cell proliferation, whereas loss of either NHP2 or NOP10 had no effect. Finally, loss of dyskerin, GAR1, NHP2, and NOP10, respectively, limited the accumulation of DNA damage biomarkers. However, the individual responses were dependent upon the specific type of damage incurred. In general, loss of GAR1 had the most suppressive effect on the biomarkers tested. Since the specific responses to genotoxic stress, the contribution of each protein to cell proliferation, and the activation of DNA damage biomarkers were not equivalent, this suggests the possibility that at least some of the proteins, most notably GAR1, may potentially function independently of their respective roles within H/ACA RNP complexes.

Acute dyskerin depletion triggers cellular senescence and renders osteosarcoma cells resistant to genotoxic stress-induced apoptosis.

Dyskerin is a conserved, nucleolar RNA-binding protein implicated in an increasing array of fundamental cellular processes. Germline mutation in the dyskerin gene (DKC1) is the cause of X-linked dyskeratosis congenita (DC). Conversely, wild-type dyskerin is overexpressed in sporadic cancers, and high-levels may be associated with poor prognosis. It was previously reported that acute loss of dyskerin function via siRNA-mediated depletion slowed the proliferation of transformed cell lines. However, the mechanisms remained unclear. Using human U2OS osteosarcoma cells, we show that siRNA-mediated dyskerin depletion induced cellular senescence as evidenced by proliferative arrest, senescence-associated heterochromatinization and a senescence-associated molecular profile. Senescence can render cells resistant to apoptosis. Conversely, chromatin relaxation can reverse the repressive effects of senescence-associated heterochromatinization on apoptosis. To this end, genotoxic stress-induced apoptosis was suppressed in dyskerin-depleted cells. In contrast, agents that induce chromatin relaxation, including histone deacetylase inhibitors and the DNA intercalator chloroquine, sensitized dyskerin-depleted cells to apoptosis. Dyskerin is a core component of the telomerase complex and plays an important role in telomere homeostasis. Defective telomere maintenance resulting in premature senescence is thought to primarily underlie the pathogenesis of X-linked DC. Since U2OS cells are telomerase-negative, this leads us to conclude that loss of dyskerin function can also induce cellular senescence via mechanisms independent of telomere shortening.

Disruption of H3K36 methylation provokes cellular plasticity to drive aberrant glandular formation and squamous carcinogenesis.

Chromatin organization is essential for maintaining cell-fate trajectories and developmental programs. Here, we find that disruption of H3K36 methylation dramatically impairs normal epithelial differentiation and development, which promotes increased cellular plasticity and enrichment of alternative cell fates. Specifically, we observe a striking increase in the aberrant generation of excessive epithelial glandular tissues, including hypertrophic salivary, sebaceous, and meibomian glands, as well as enhanced squamous tumorigenesis. These phenotypic and gene expression manifestations are associated with loss of H3K36me2 and rewiring of repressive H3K27me3, changes we also observe in human patients with glandular hyperplasia. Collectively, these results have identified a critical role for H3K36 methylation in both in vivo epithelial cell-fate decisions and the prevention of squamous carcinogenesis and suggest that H3K36 methylation modulation may offer new avenues for the treatment of numerous common disorders driven by altered glandular function, which collectively affect large segments of the human population.

Diabetes aggravates periodontitis by limiting repair through enhanced inflammation.

Periodontitis is the most common lytic bone disease and one of the first clinical manifestations of diabetes. Diabetes increases the risk of periodontitis. The aim of the present study was to examine mechanisms by which diabetes aggravates periodontitis. Ligature-induced periodontitis was examined in Goto-Kakizaki rats with type 2 diabetes. A tumor necrosis factor (TNF)-specific-inhibitor, pegsunercept, was applied to diabetic rats after the onset of periodontal disease. Interferon-γ (IFN-γ), TNF-α, interleukin-1 ß (IL-1ß), fibroblast growth factor-2 (FGF-2), transforming growth factor beta-1 (TGFß-1), bone morphogenetic protein-2 (BMP-2), and BMP-6 were measured by real-time RT-PCR, and histological sections were examined for leukocyte infiltration and several parameters related to bone resorption and formation. Inflammation was prolonged in diabetic rats and was reversed by the TNF inhibitor, which reduced cytokine mRNA levels, leukocyte infiltration, and osteoclasts. In contrast, new bone and osteoid formation and osteoblast numbers were increased significantly vs. untreated diabetic animals. TNF inhibition in diabetic animals also reduced apoptosis, increased proliferation of bone-lining cells, and increased mRNA levels of FGF-2, TGFß-1, BMP-2, and BMP-6. Thus, diabetes prolongs inflammation and osteoclastogenesis in periodontitis and through TNF limits the normal reparative process by negatively modulating factors that regulate bone.

Oral involvement of cutaneous T-cell lymphoma: A rare entity.

Mycosis fungoides (MF) is a rare cutaneous T-cell lymphoma (CTCL) with significant morbidity and mortality rates. Involvement of MF in the oral cavity is uncommon, often follows cutaneous involvement, and is usually associated with a poor prognosis. Herein, we describe a case of a 72-year-old White male with biopsy-proven oral T-cell lymphoma (TCL) in the setting of MF with systemic disease progression. Mycosis fungoides with oral involvement can often prove challenging to diagnose and manage. Thorough medical history intake and clinical examination supported by histopathologic and immunohistochemical analysis are imperative because delay in the diagnosis can lead to disease progression.

A Periodontal Perspective on the Successful Treatment of Recurrent Benign Gingival Lesions Affecting the Anterior Dentition: Two Case Reports.

Recurrent benign gingival lesions occurring in the anterior dentition are clinical dilemmas. While complete removal of such lesions is required to prevent recurrence, this can result in a poor esthetic outcome. Relative to this conundrum, this report discusses the diagnosis, psychologic management, and clinical treatment of two patients with recurring lesions on the facial gingiva of the mandibular and maxillary incisors, respectively. Patient A, a 55-year-old woman, presented with a recurrent peripheral ossifying fibroma (POF); Patient B, a 76-year-old man, presented with a recurrent pyogenic granuloma (PG). Both patients underwent multiple procedures and were ultimately treated without lesion recurrence. The efficacious surgical treatment of recurrent gingival lesions like POF and PG requires an aggressive approach involving lesion removal of the lesion as well as a 1.0- to 2.0-mm margin of normal tissue, underlying alveolar bone, and associated periodontal ligament (PDL). The rationale for this approach stresses the potential periodontal and esthetic ramifications that were considered. In summary, when recurrent benign gingival lesions are localized to the anterior part of the mouth, the approach to their surgical removal should be modified to minimize the extent of gingival recession and other potential esthetic issues.

Iron oxide nanozymes stabilize stannous fluoride for targeted biofilm killing and synergistic oral disease prevention.

Dental caries (tooth decay) is the most prevalent human disease caused by oral biofilms, affecting nearly half of the global population despite increased use of fluoride, the mainstay anticaries (tooth-enamel protective) agent. Recently, an FDA-approved iron oxide nanozyme formulation (ferumoxytol, Fer) has been shown to disrupt caries-causing biofilms with high specificity via catalytic activation of hydrogen peroxide, but it is incapable of interfering with enamel acid demineralization. Here, we find notable synergy when Fer is combined with stannous fluoride (SnF 2 ), markedly inhibiting both biofilm accumulation and enamel damage more effectively than either alone. Unexpectedly, our data show that SnF 2 enhances the catalytic activity of Fer, significantly increasing reactive oxygen species (ROS) generation and antibiofilm activity. We discover that the stability of SnF 2 (unstable in water) is markedly enhanced when mixed with Fer in aqueous solutions without any additives. Further analyses reveal that Sn 2+ is bound by carboxylate groups in the carboxymethyl-dextran coating of Fer, thus stabilizing SnF 2 and boosting the catalytic activity. Notably, Fer in combination with SnF 2 is exceptionally effective in controlling dental caries in vivo , preventing enamel demineralization and cavitation altogether without adverse effects on the host tissues or causing changes in the oral microbiome diversity. The efficacy of SnF 2 is also enhanced when combined with Fer, showing comparable therapeutic effects at four times lower fluoride concentration. Enamel ultrastructure examination shows that fluoride, iron, and tin are detected in the outer layers of the enamel forming a polyion-rich film, indicating co-delivery onto the tooth surface. Overall, our results reveal a unique therapeutic synergism using approved agents that target complementary biological and physicochemical traits, while providing facile SnF 2 stabilization, to prevent a widespread oral disease more effectively with reduced fluoride exposure.

Iron oxide nanozymes stabilize stannous fluoride for targeted biofilm killing and synergistic oral disease prevention.

Dental caries is the most common human disease caused by oral biofilms despite the widespread use of fluoride as the primary anticaries agent. Recently, an FDA-approved iron oxide nanoparticle (ferumoxytol, Fer) has shown to kill and degrade caries-causing biofilms through catalytic activation of hydrogen peroxide. However, Fer cannot interfere with enamel acid demineralization. Here, we show notable synergy when Fer is combined with stannous fluoride (SnF2), markedly inhibiting both biofilm accumulation and enamel damage more effectively than either alone. Unexpectedly, we discover that the stability of SnF2 is enhanced when mixed with Fer in aqueous solutions while increasing catalytic activity of Fer without any additives. Notably, Fer in combination with SnF2 is exceptionally effective in controlling dental caries in vivo, even at four times lower concentrations, without adverse effects on host tissues or oral microbiome. Our results reveal a potent therapeutic synergism using approved agents while providing facile SnF2 stabilization, to prevent a widespread oral disease with reduced fluoride exposure.

Gingival Overgrowth in an Adult Male Patient.

Pyogenic granuloma (PG) is an oral reactive inflammatory hyperplasia of connective tissue that can occur in response to hormonal changes and local irritation such as calculus, fractured teeth, rough dental restorations, and foreign materials. It is nonneoplastic and predominant in the second decade of life in young adult females. The most common site of involvement is the gingiva. Lesions are more common in the maxillary than mandibular gingiva and mainly occur on the facial or buccal aspect. Pyogenic granuloma rarely grows more than 2 cm in diameter and is rarely associated with bone loss. This article presents a rare case of an abnormally large pyogenic granuloma affecting both the labial and palatal gingiva sustaining occlusal trauma due to its size and associated with severe alveolar bone loss that was managed successfully with surgical excision in a 40-year-old male.

Immediate impact of dental prophylaxis and oral hygiene improvement on multifocal pyogenic granulomas: a case report.

A 31-year-old man presented with gingival mass-like lesions. The patient reported occasional bleeding from lesions; otherwise, the lesions were asymptomatic. Intraoral examination revealed multiple interdental red/purple soft, sessile, nodular lesions involving both the maxillary and mandibular buccal and lingual gingivae, with poor oral hygiene. After performing incisional biopsy, the patient was diagnosed with pyogenic granuloma. Subsequently, the patient underwent cleaning of his teeth and within only 3 days of dental cleaning, the patient reported rapid regression of all his lesions.

EBV-positive B-cell ulcerative proliferation in the oral cavity associated with EBV-negative follicular lymphoma in a patient with common variable immunodeficiency: A case report and review of the literature.

Lymphoproliferative disorders (LPDs) are a group of conditions characterized by excessive production of lymphocytes manifested in various patterns including lymphadenopathy, tumor-like lesions, and lymphomas. LPD may be stimulated by Epstein-Barr virus (EBV) infection that most commonly appears in the setting of immunocompromised status such as long-term use of immunosuppressive medications and in individuals with primary immunodeficiency disorders. EBV mucocutaneous ulcer is a benign LPD reaction that mostly regresses spontaneously but sometimes requires medical or surgical intervention. This article presents a case of oral EBV mucocutaneous ulceration that affected an individual with a history of complex primary immunodeficiency disorders consisted of common variable immunodeficiency disease associated with T-cell dysfunction. This case is unique because the oral lesions led to the diagnosis of concurrent widespread EBV-negative follicular lymphomas, seemingly unrelated to her EBV-positive LPD oral disease. Yet, both occurred in the setting of severe immunosuppression from the primary immunodeficiency disorders.

NF-κB perturbation reveals unique immunomodulatory functions in Prx1+ fibroblasts that promote development of atopic dermatitis.

Skin is composed of diverse cell populations that cooperatively maintain homeostasis. Up-regulation of the nuclear factor κB (NF-κB) pathway may lead to the development of chronic inflammatory disorders of the skin, but its role during the early events remains unclear. Through analysis of single-cell RNA sequencing data via iterative random forest leave one out prediction, an explainable artificial intelligence method, we identified an immunoregulatory role for a unique paired related homeobox-1 (Prx1)+ fibroblast subpopulation. Disruption of Ikkb-NF-κB under homeostatic conditions in these fibroblasts paradoxically induced skin inflammation due to the overexpression of C-C motif chemokine ligand 11 (CCL11; or eotaxin-1) characterized by eosinophil infiltration and a subsequent TH2 immune response. Because the inflammatory phenotype resembled that seen in human atopic dermatitis (AD), we examined human AD skin samples and found that human AD fibroblasts also overexpressed CCL11 and that perturbation of Ikkb-NF-κB in primary human dermal fibroblasts up-regulated CCL11. Monoclonal antibody treatment against CCL11 was effective in reducing the eosinophilia and TH2 inflammation in a mouse model. Together, the murine model and human AD specimens point to dysregulated Prx1+ fibroblasts as a previously unrecognized etiologic factor that may contribute to the pathogenesis of AD and suggest that targeting CCL11 may be a way to treat AD-like skin lesions.

Dyskerin is required for tumor cell growth through mechanisms that are independent of its role in telomerase and only partially related to its function in precursor rRNA processing.

Dyskerin is an essential nucleolar protein required for the biogenesis of ribonucleoproteins that incorporate H/ACA RNAs. Through binding to specific H/ACA RNAs, dyskerin exerts most of its influence in the cell. To that end, dyskerin is a core component of the telomerase complex and is required for normal telomere maintenance. Dyskerin is also required for post-transcriptional processing of precursor rRNA. Germline dyskerin mutations increase cancer susceptibility. Conversely, wild-type dyskerin is usually over-expressed and not mutated in sporadic cancers. However, the contributions of dyskerin to sporadic tumorigenesis are unknown. Described herein, we demonstrate that acute loss of dyskerin function by RNA interference significantly reduced steady-state levels of H/ACA RNAs, disrupted the morphology and inhibited anchorage-independent growth of telomerase-positive and telomerase-negative human cell lines. Unexpectedly, dyskerin depletion only transiently delayed rRNA maturation but with no appreciable effect on the levels of total 18S or 28S rRNA. Instead, while rRNA processing defects typically trigger p53-dependent G1 arrest, dyskerin-depleted cells accumulated in G2/M by a p53-independent mechanism, and this was associated with an accumulation of aberrant mitotic figures that were characterized by multi-polar spindles. Telomerase activity and the rate of rRNA processing are typically increased during neoplasia. However, our cumulative findings indicate that dyskerin contributes to tumor cell growth through mechanisms which do not require the presence of cellular telomerase activity, and which may be only partially dependent upon the protein's role in rRNA processing. These data also reinforce the notion that loss and gain of dyskerin function may play important roles in tumorigenesis.

An amelogenin mutation leads to disruption of the odontogenic apparatus and aberrant expression of Notch1.

BACKGROUND: Amelogenins are highly conserved proteins secreted by ameloblasts in the dental organ of developing teeth. These proteins regulate dental enamel thickness and structure in humans and mice. Mice that express an amelogenin transgene with a P70T mutation (TgP70T) develop abnormal epithelial proliferation in an amelogenin null (KO) background. Some of these cellular masses have the appearance of proliferating stratum intermedium, which is the layer adjacent to the ameloblasts in unerupted teeth. As Notch proteins are thought to constitute the developmental switch that separates ameloblasts from stratum intermedium, these signaling proteins were evaluated in normal and proliferating tissues. METHODS: Mandibles were dissected for histology and immunohistochemistry using Notch1 antibodies. Molar teeth were dissected for western blotting and RT-PCR for evaluation of Notch levels through imaging and statistical analyses. RESULTS: Notch1 was immunolocalized to ameloblasts of TgP70TKO mice, KO ameloblasts stained, but less strongly, and wild-type teeth had minimal staining. Cells within the proliferating epithelial cell masses were positive for Notch1 and had an appearance reminiscent of calcifying epithelial odontogenic tumor with amyloid-like deposits. Notch1 protein and mRNA were elevated in molar teeth from TgP70TKO mice. CONCLUSION: Expression of TgP70T leads to abnormal structures in mandibles and maxillae of mice with the KO genetic background and these mice have elevated levels of Notch 1 in developing molars. As cells within the masses also express transgenic amelogenins, development of the abnormal proliferations suggests communication between amelogenin producing cells and the proliferating cells, dependent on the presence of the mutated amelogenin protein.