ß-catenin/CBP activation of mTORC1 signaling promotes partial epithelial-mesenchymal states in head and neck cancer.

Head and neck cancers, which include oral squamous cell carcinoma (OSCC) as a major subsite, exhibit cellular plasticity that includes features of an epithelial-mesenchymal transition (EMT), referred to as partial-EMT (p-EMT). To identify molecular mechanisms contributing to OSCC plasticity, we performed a multiphase analysis of single cell RNA sequencing (scRNAseq) data from human OSCC. This included a multiresolution characterization of cancer cell subgroups to identify pathways and cell states that are heterogeneously represented, followed by casual inference analysis to elucidate activating and inhibitory relationships between these pathways and cell states. This approach revealed signaling networks associated with hierarchical cell state transitions, which notably included an association between ß-catenin-driven CREB-binding protein (CBP) activity and mTORC1 signaling. This network was associated with subpopulations of cancer cells that were enriched for markers of the p-EMT state and poor patient survival. Functional analyses revealed that ß-catenin/CBP induced mTORC1 activity in part through the transcriptional regulation of a raptor-interacting protein, chaperonin containing TCP1 subunit 5 (CCT5). Inhibition of ß-catenin-CBP activity through the use of the orally active small molecule, E7386, reduced the expression of CCT5 and mTORC1 activity in vitro, and inhibited p-EMT-associated markers and tumor development in a murine model of OSCC. Our study highlights the use of multiresolution network analyses of scRNAseq data to identify targetable signals for therapeutic benefit, thus defining an underappreciated association between ß-catenin/CBP and mTORC1 signaling in head and neck cancer plasticity.

Impact of depth of invasion on local recurrence in R0 resected node-negative oral tongue squamous cell carcinoma.

BACKGROUND: This study evaluates the impact of depth of invasion (DOI) on local recurrence (LR) in node-negative oral tongue squamous cell carcinoma (SCC). METHODS: Fifty-one patients were retrospectively reviewed from an institutional database. Patients were evaluated for local control (LC). Cox-proportional hazards modeling was used to calculate hazard ratios. RESULTS: There were 84.3% T1/2 and 15.7% T3/4 classification tumors. The 3-year overall survival rate was 97.9%. Local failure rate was 5.7% with a 3-year LC of 93.6%. On Univariate analysis, increased hazard of LR was noted with each unit increase in DOI (HR 1.40, 95% CI 1.07-1.83, p = 0.014). Age, sex, T classification, margins ≥5 mm, lymphovascular invasion (LVI) and perineural invasion (PNI), and adjuvant treatment were not associated with LR. On Multivariate analysis, adjusting for age and adjuvant treatment, results for DOI remained significant (aHR 1.46, 95% CI 1.08-1.98, p = 0.013). CONCLUSION: On evaluation of our institutional dataset increasing DOI was associated with increased hazard of local recurrence with oral tongue SCC.

Inhibition of LSD1 Attenuates Oral Cancer Development and Promotes Therapeutic Efficacy of Immune Checkpoint Blockade and YAP/TAZ Inhibition.

Lysine-specific demethylase 1 (LSD1) is a histone demethylase that contributes to the etiology of oral squamous cell carcinoma (OSCC) in part by promoting cancer stem cell phenotypes. The molecular signals regulated by LSD1, or acting with LSD1, are poorly understood, particularly in the development of OSSC. In this study, we show that conditional deletion of the Lsd1 gene or pharmacologic inhibition of LSD1 in the tongue epithelium leads to reduced development of OSCC following exposure to the tobacco carcinogen 4NQO. LSD1 inhibition attenuated proliferation and clonogenic survival and showed an additive effect when combined with the YAP inhibitor Verteporfin. Interestingly, LSD1 inhibition upregulated the expression of PD-L1, leading to immune checkpoint inhibitor therapy responses. IMPLICATIONS: Collectively, our studies reveal a critical role for LSD1 in OSCC development and identification of tumor growth targeting strategies that can be combined with LSD1 inhibition for improved therapeutic application.

Treatment of tophaceous pseudogout in the temporomandibular joint with resection and alloplastic reconstruction: a single-staged approach.

Tophaceous pseudogout is a rare variant of the calcium pyrophosphate dihydrate (CPPD) disorder, with predilection for the TMJ. It is characterized by calcific deposits composed of rhomboid- or rectangular-shaped crystals that exhibit birefringence when examined under polarized light. We hereby present a case of a 65-year-old man with left pre-auricular tenderness and malocclusion. CT imaging was notable for a left TMJ mineralized mass with erosion of the condylar head. Treatment involved excision of the mass with eminectomy, condylectomy, and a stock total TMJ reconstruction. In this report, important considerations for diagnosis, biopsy, and surgical treatment with emphasis on reconstruction for tophaceous pseudogout of the TMJ have been highlighted by the authors.

Oral hairy leukoplakia: a series of 45 cases in immunocompetent patients.

OBJECTIVE: Oral hairy leukoplakia (OHL) is a benign Epstein-Barr virus infection typically presenting as a white lesion on the lateral border of the tongue. Historically, OHL was described in patients who are severely immunocompromised, such as those with HIV/AIDS and organ transplant patients. OHL is increasingly seen in patients who are not severely immunocompromised. This study reviews 45 cases of OHL in a single institution and characterizes the clinical features of these relatively immunocompetent patients. STUDY DESIGN: Retrospective study. RESULTS: There were 45 cases with 23 male patients (51.1%) and a median age of 64 (range, 24-100 years). The lateral/ventral tongue was the affected site in 41 cases (91.1%), and 5 cases presented bilaterally. A review of the medical history and medications showed the most common conditions were hypertension (53.3%), hyperlipidemia (42.2%), and chronic respiratory conditions (33.3%); 8 patients (17.8%) had diabetes mellitus, and 1 had rheumatoid arthritis. Eleven cases (24.4%) reported no underlying medical conditions or history of medications. The most frequently reported medications included antihypertensive drugs (21.0%), steroid inhalers (14.6%), and cholesterol-lowering drugs (11.0%). CONCLUSIONS: OHL is not exclusively seen in profoundly immunocompromised patients. Localized immunosuppression (from steroid inhalers) and immunosenescence (aging) are possible contributing factors.

Diatoms: A novel cause of granulomatous inflammation of the head and neck.

OBJECTIVE: We report the first 4 cases of intraoral nonnecrotizing granulomatous foreign body reactions to diatoms, plausibly as a result of exogenous material introduced following iatrogenic or traumatic injury. STUDY DESIGN: Clinical and histopathologic findings of 4 intraoral cases of nonnecrotizing granulomatous foreign body reaction to diatoms, single-celled algae belonging to the taxonomic phylum Bacillariophyta, are reported. RESULTS: The lesions presented either in the jaws or in the soft tissue overlying the alveolar bone, in some instances mimicking an inflammatory lesion of odontogenic etiology. Microscopically, the lesions presented as nonnecrotizing granulomatous inflammation associated with either spherical and radially symmetric or rectangular and bilaterally symmetric diatomaceous foreign material. CONCLUSION: The diagnosis of a diatom-associated foreign body reaction necessitates familiarization with the histopathologic features of these organisms to accurately characterize the nature of such lesions.

Mechanism for oral tumor cell lysyl oxidase like-2 in cancer development: synergy with PDGF-AB.

Extracellular lysyl oxidases (LOX and LOXL1-LOXL4) are critical for collagen biosynthesis. LOXL2 is a marker of poor survival in oral squamous cell cancer. We investigated mechanisms by which tumor cell secreted LOXL2 targets proximal mesenchymal cells to enhance tumor growth and metastasis. This study identified the first molecular mechanism for LOXL2 in the promotion of cancer via its enzymatic modification of a non-collagenous substrate in the context of paracrine signaling between tumor cells and resident fibroblasts. The role and mechanism of active LOXL2 in promoting oral cancer was evaluated and employed a novel LOXL2 small molecule inhibitor, PSX-S1C, administered to immunodeficient, and syngeneic immunocompetent orthotopic oral cancer mouse models. Tumor growth, histopathology, and metastases were monitored. In vitro mechanistic studies with conditioned tumor cell medium treatment of normal human oral fibroblasts were carried out in the presence and absence of the LOXL2 inhibitor to identify signaling mechanisms promoted by LOXL2 activity. Inhibition of LOXL2 attenuated cancer growth and lymph node metastases in the orthotopic tongue mouse models. Immunohistochemistry data indicated that LOXL2 expression in and around tumors was decreased in mice treated with the inhibitor. Inhibition of LOXL2 activity by administration of PXS-S1C to mice reduced tumor cell proliferation, accompanied by changes in morphology and in the expression of epithelial to mesenchymal transition markers. In vitro studies identified PDGFRß as a direct substrate for LOXL2, and indicated that LOXL2 and PDGF-AB together secreted by tumor cells optimally activated PDGFRß in fibroblasts to promote proliferation and the tendency toward fibrosis via ERK activation, but not AKT. Optimal fibroblast proliferation in vitro required LOXL2 activity, while tumor cell proliferation did not. Thus, tumor cell-derived LOXL2 in the microenvironment directly targets neighboring resident cells to promote a permissive local niche, in addition to its known role in collagen maturation.

Idiopathic gingival papillokeratosis with crypt formation, a report of 7 cases of a previously undescribed entity: possible unusual oral epithelial nevus?

We report 7 cases of hitherto undescribed keratotic papillary plaques of uncertain etiology involving the gingiva. All 7 cases presented on the anterior maxillary attached gingiva of patients in the second decade. The lesions were asymptomatic and 86% (6 of 7 cases) presented in a bilateral symmetric distribution. Microscopically, the lesions exhibited parakeratosis and papillary acanthosis with parakeratin-filled crypts. No specific etiology such as a factitial habit or a common exogenous agent has been identified. The possibility of a developmental etiology such as an oral epithelial nevus cannot be entirely excluded. We propose the descriptive term idiopathic gingival papillokeratosis with crypt formation (IGPC) for this condition.

The root of the problem: Occurrence of typical and atypical periapical pathoses.

BACKGROUND: A preponderance of periapical radiolucencies are of inflammatory etiology (radicular cysts or periapical granulomas) secondary to pulpal disease. In some instances, however, a suspected periapical inflammatory lesion is not a consequence of pulpal disease but instead represents a lesion of noninflammatory origin. The differential diagnosis for such lesions is broad, ranging from odontogenic cysts and tumors to metastatic disease. As the biological behavior of such lesions is varied, the distinction between inflammatory odontogenic periapical lesions and lesions of noninflammatory origin in a periapical location is critical. METHODS: A retrospective study of 5,993 archival periapical biopsies over a span of 15 years from the database of the Oral Pathology Biopsy Service in the Henry M. Goldman School of Dental Medicine at Boston University recorded the incidence of various lesions in a periapical location. RESULTS: Of the cases studied, 97.2% represented lesions of inflammatory origin with histopathologic diagnoses as follows: periapical granuloma (60.0%), radicular cyst (36.7%), periapical fibrous scar (0.27 %), and periapical abscess (0.23 %). The remaining 2.8% cases were lesions of noninflammatory origin with histopathologic diagnoses of odontogenic keratocyst (also known as keratocystic odontogenic tumor), benign fibro-osseous lesions, and ameloblastoma. One patient had Langerhans cell disease, and 1 had central giant cell granuloma. CONCLUSIONS: Although most periapical specimens biopsied represented expected inflammatory periapical lesions, the biological behavior of underdiagnosed lesions may have considerable consequences for both the patient and the clinician. PRACTICAL IMPLICATIONS: This article serves to inform clinicians regarding the diversity of lesions arising in the periapical region of the jaws, to assist in the formulation of differential diagnoses, and to highlight the importance of submission of lesional tissue for histopathologic evaluation and definitive diagnosis when biopsy is clinically indicated.

PDGFRß Is a Novel Marker of Stromal Activation in Oral Squamous Cell Carcinomas.

Carcinoma associated fibroblasts (CAFs) form the main constituents of tumor stroma and play an important role in tumor growth and invasion. The presence of CAFs is a strong predictor of poor prognosis of head and neck squamous cell carcinoma. Despite significant progress in determining the role of CAFs in tumor progression, the mechanisms contributing to their activation remain poorly characterized, in part due to fibroblast heterogeneity and the scarcity of reliable fibroblast surface markers. To search for such markers in oral squamous cell carcinoma (OSCC), we applied a novel approach that uses RNA-sequencing data derived from the cancer genome atlas (TCGA). Specifically, our strategy allowed for an unbiased identification of genes whose expression was closely associated with a set of bona fide stroma-specific transcripts, namely the interstitial collagens COL1A1, COL1A2, and COL3A1. Among the top hits were genes involved in cellular matrix remodeling and tumor invasion and migration, including platelet-derived growth factor receptor beta (PDGFRß), which was found to be the highest-ranking receptor protein genome-wide. Similar analyses performed on ten additional TCGA cancer datasets revealed that other tumor types shared CAF markers with OSCC, including PDGFRß, which was found to significantly correlate with the reference collagen expression in ten of the 11 cancer types tested. Subsequent immunostaining of OSCC specimens demonstrated that PDGFRß was abundantly expressed in stromal fibroblasts of all tested cases (12/12), while it was absent in tumor cells, with greater specificity than other known markers such as alpha smooth muscle actin or podoplanin (3/11). Overall, this study identified PDGFRß as a novel marker of stromal activation in OSCC, and further characterized a list of promising candidate CAF markers that may be relevant to other carcinomas. Our novel approach provides for a fast and accurate method to identify CAF markers without the need for large-scale immunostaining experiments.