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.

Comparing the Diagnostic Accuracy of Ultrasonography, CT, MRI, and PET/CT in Cervical Lymph Node Metastasis of Oral Squamous Cell Carcinoma.

(1) Background: In oral cancer staging, ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) with positron emission tomography/computed tomography (PET/CT) are routinely used in clinical practice. The present study is a retrospective examination of the diagnostic accuracy of cervical lymph node metastasis using US, CT, MRI, and PET/CT, with histopathological diagnosis as a reference, to compare the different diagnostic imaging modalities. (2) Methods: The participants included 16 patients with oral squamous cell carcinoma who underwent US-, CT-, MRI-, and PET/CT-based preoperative diagnostic imaging and simultaneous primary lesion resection and neck dissection, including 82 level regions and 424 lymph nodes. We compared the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of each imaging modality based on the imaging results and the pathology results of metastasis. (3) Results: Of the four diagnostic imaging modalities, PET/CT exhibited the highest sensitivity but the lowest specificity and accuracy. US, CT, and MRI had high specificities. Comparing each level region and lymph node showed that differences were observed in PET/CT. (4) Conclusions: PET/CT to diagnose lymph node metastasis requires a comprehensive evaluation because it produces more false positives than other diagnostic imaging modalities. Using US, CT, and MRI, which have excellent spatial resolution, improves diagnostic accuracy at the lymph node level.

Hypoxia-Induced Biosynthesis of the Extracellular Matrix Molecules, Perlecan and Fibronectin, Promotes the Growth of Pleomorphic Adenoma Cells In Vitro Models.

Salivary pleomorphic adenoma is histopathologically characterized by its colorful stroma with myxoid, chondroid, and hyaline appearances, due to enhanced biosynthesis of extracellular matrix (ECM) molecules and poor vascularity. Thus, pleomorphic adenoma cells embedded in the stroma typically survive under hypoxic conditions. We determined the expression kinetics of ECM molecules, such as perlecan and fibronectin (FN), under hypoxia in SM-AP1 cells which are duct epithelial differentiated cells, and in SM-AP4 cells, which are myoepithelial differentiated cells, cloned from pleomorphic adenoma of the parotid gland. We investigated hypoxia-inducible factor-1α (HIF-1α)-inducing pathways through a variety of ECM molecules in association with their cellular proliferation and migration. We observed that hypoxic conditions with elevated HIF-1α protein levels induced increased expression of perlecan and FN in SM-AP cells than in controls. Moreover, perlecan and FN knockdown reduced the proliferation of SM-AP1 and SM-AP4 cells under hypoxia. Further, SM-AP1 cell migration was enhanced by both perlecan and FN knockdown, whereas SM-AP4 cell migration was increased by perlecan knockdown and inhibited by fibronectin knockdown. The results indicated that pleomorphic adenoma cells can survive under hypoxic conditions by promoting cell proliferation via enhanced synthesis of ECM molecules. Overall, ECM molecules may be a new anti-tumor target under hypoxic conditions.

Masticatory muscle tendon-aponeurosis hyperplasia that was initially misdiagnosed for polymyositis: a case report and review of the literature.

BACKGROUND: Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a relatively newly identified clinical condition that manifests as trismus with a square-shaped mandible. Herein, we report a case of MMATH that was initially misdiagnosed for polymyositis due to trismus and simultaneous lower limb pain, with literature review. CASE PRESENTATION: A 30-year-old woman had a history of lower limb pain after exertion for 2 years. Initial physical examination had been performed at the Department of General Medicine in our hospital. There was also redness in the hands and fingers. Although polymyositis was suspected, it was denied. The patient visited our department for right maxillary wisdom tooth extraction. Clinical examination revealed that the patient had a square-shaped mandible. The maximal mouth opening was 22 mm. There was no temporomandibular joint pain at the time of opening. Furthermore, there was awareness of clenching while working. Panoramic radiography revealed developed square mandibular angles with flattened condyles. Computed tomography showed enlarged masseter muscles with high-density areas around the anterior and lateral fascia. Magnetic resonance imaging also showed thickened tendons and aponeuroses on the anterior surface and inside bilateral masseter muscles. Finally, the patient was diagnosed with MMTAH. Bilateral aponeurectomy of the masseter muscles with coronoidectomy and masseter muscle myotomy was performed under general anesthesia. The maximum opening during surgery was 48 mm. Mouth opening training was started on day 3 after surgery. Histopathological examination of the surgical specimen showed that the muscle fibers were enlarged to 60 µm. Immunohistochemistry testing for calcineurin, which was associated with muscle hypertrophy due to overload in some case reports, showed positive results. Twelve months after surgery, the mouth self-opening and forced opening were over 35 mm and 44 mm, respectively. CONCLUSIONS: Herein, we report a case of MMATH. Lower limb pain due to prolonged standing at work and overload due to clenching were considered risk factors for symptoms onset of MMATH.

Cholesterol Is a Regulator of CAV1 Localization and Cell Migration in Oral Squamous Cell Carcinoma.

Cholesterol plays an important role in cancer progression, as it is utilized in membrane biogenesis and cell signaling. Cholesterol-lowering drugs have exhibited tumor-suppressive effects in oral squamous cell carcinoma (OSCC), suggesting that cholesterol is also essential in OSCC pathogenesis. However, the direct effects of cholesterol on OSCC cells remain unclear. Here, we investigated the role of cholesterol in OSCC with respect to caveolin-1 (CAV1), a cholesterol-binding protein involved in intracellular cholesterol transport. Cholesterol levels in OSCC cell lines were depleted using methyl-ß-cyclodextrin and increased using the methyl-ß-cyclodextrin-cholesterol complex. Functional analysis was performed using timelapse imaging, and CAV1 expression in cholesterol-manipulated cells was investigated using immunofluorescence and immunoblotting assays. CAV1 immunohistochemistry was performed on surgical OSCC samples. We observed that cholesterol addition induced polarized cell morphology, along with CAV1 localization at the trailing edge, and promoted cell migration. Moreover, CAV1 was upregulated in the lipid rafts and formed aggregates in the plasma membrane in cholesterol-added cells. High membranous CAV1 expression in tissue specimens was associated with OSCC recurrence. Therefore, cholesterol promotes the migration of OSCC cells by regulating cell polarity and CAV1 localization to the lipid raft. Furthermore, membranous CAV1 expression is a potential prognostic marker for OSCC patients.

Liquid-based cytology for differentiating two cases of pemphigus vulgaris from oral squamous cell carcinoma.

Pemphigus vulgaris (PV) is a rare autoimmune disease characterized by blisters on the skin and mucous membrane. Since it often appears in the oral mucosa first, it may be diagnosed by oral mucosal cytology. Although the cytologic finding is characterized by acantholytic cells, that is, Tzanck cells, it is important to distinguish PV from neoplastic lesions of the oral mucosal epithelium, including differentiation from atypical parabasal/basal cells, which appear in squamous cell carcinoma (SCC). In this study, we examined the cellular findings in two cases of PV and a case of well-differentiated SCC with loss of epithelial cell cohesion. The samples were prepared using liquid-based cytology, which showed small round-shaped and deeply stained atypical, orangeophilic keratinocytes not only in SCC but also in PV, which made differentiation between the two difficult. However, Tzanck cells found in PV differ from the deep atypical parabasal/basal cells of SCC, suggesting that the cell outline is indistinct and small protrusions and brush-like structures are observed. This feature of Tzanck cells may be useful in cytological judgment.

Clinicopathologic factors influencing the screening accuracy of oral cytology: A retrospective cohort study.

Cytology is a simple and non-invasive screening method for oral cancer. However, this method is not yet routinely used by clinicians because of its high false negative rate (FNR) and due to lack of sufficient studies examining the factors for high FNRs. The present retrospective study aimed to compare the screening performance of conventional cytology (CC) and liquid-based cytology (LBC) through histological validation, and to elucidate factors inducing false negative screening in oral cytology. Cytological specimens with histological examination and intraoral digital images of the lesion were retrospectively collected between January 2017 and December 2018 for CC and between October 2019 and September 2021 for LBC. Oral cytological screening was conducted based on the oral Bethesda system for oral cytology. Clinical subtypes were re-evaluated using intraoral digital images. The screening accuracy of oral cytology was calculated considering the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting the malignant transformation of oral lesions. No statistically significant difference was noted in the inadequate rate between CC and LBC groups. For CC and LBC, the sensitivities were 60.9 and 59.2%, the specificities were 87.3 and 79.1%, the PPVs were 85.8 and 76.2%, and the NPVs were 63.9 and 63.2%, respectively. Thus, the screening accuracy was similar between methodologies. Among the clinicopathological factors investigated, histological diagnosis and cellularity contributed to false negative results. Homogeneous findings of oral epithelial dysplasia and the superficial growth of carcinoma in situ/squamous cell carcinoma resulted in false negative findings for CC and LBC. Furthermore, LBC samples with a lower cell number (<2,000 squamous cells) exhibited statistically significantly increased FNRs. The present study found that the cytological methods did not affect the inadequate rate and screening accuracy, whereas clinical subtype and cellularity decreased screening accuracy. Therefore, cytological screening and subsequent follow-up should be performed while considering clinical findings and the cellularity of cytology smears.

Adenosquamous Carcinoma with the Acantholytic Feature in the Oral Cavity: A Case Report and Comprehensive Literature Review.

Adenosquamous carcinoma (ASC) is an aggressive subtype of squamous cell carcinoma (SCC). Due to its poor prognosis, a precise pathological diagnosis of ASC is essential but challenging because its pathological criteria are still unclear. Here, we present a rare case of oral ASC accompanied by acantholytic features. The tumor was raised in the mandibular gingiva and recurred locally approximately 13 months after the initial surgery with cervical lymph node metastasis. Pathological specimens of the primary lesion showed acantholysis in a large area of the SCC. Mucous cells, the characteristic finding indicating glandular differentiation, were imperceptible in the initial surgical specimen but increased in the locally recurrent and metastatic lymph node specimens. In a comprehensive literature review of oral ASC cases, the present case was the only case of ASC with acantholytic features. We reconfirmed that ASC has poor prognoses, such as low 5-year overall survival and disease-free survival, high locoregional recurrence, and high distant metastasis rates. A precise diagnosis of ASC is required for estimating prognosis and undergoing close follow-up, even if the adenocarcinomatous component is limited to a small area in the lesion.

Novel cytological model for the identification of early oral cancer diagnostic markers: The carcinoma sequence model.

Most oral squamous cell carcinomas (OSCCs) arise from a premalignant lesion, oral epithelial dysplasia; however, useful markers for the early detection of OSCC are lacking. The present study aimed to establish a novel experimental model to observe changes in the sequential expression patterns of mRNAs and proteins in a rat model of tongue cancer using liquid-based cytology techniques. Cytology specimens were collected at 2, 5, 8, 11, 14, 17 and 21 weeks from rats treated with 4-nitroquinoline 1-oxide to induce tongue cancer. The expression of candidate biomarkers was examined by performing immunocytochemistry and reverse transcription-quantitative PCR. The percentage of positively stained nuclei was calculated as the labeling index (LI). All rats developed OSCC of the tongue at 21 weeks. The mRNA expression levels of bromodomain protein 4 (Brd4), c-Myc and Tp53 were upregulated during the progression from negative for intraepithelial lesion or malignancy to squamous cell carcinoma (SCC). Brd4- and c-Myc-LI increased in low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion and SCC specimens. p53-LI was significantly increased in SCC specimens. This novel experimental model allowed the observation of sequential morphological changes and the expression patterns of mRNAs and proteins during carcinogenesis. Combining immunocytochemistry with cytology-based diagnoses may potentially improve the diagnostic accuracy of OSCC.

A comparative study between CT, MRI, and intraoral US for the evaluation of the depth of invasion in early stage (T1/T2) tongue squamous cell carcinoma.

OBJECTIVES: This study aimed to clarify the accuracy of intraoral ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) in preoperative image depth of invasion (DOI) measurement of T1/T2 tongue cancer through comparison with histopathological measurements. METHODS: Imaging of the primary lesions was performed at our hospital; the lesions were classified into T1 and T2 based on the 8th edition of the AJCC/UICC, and surgery performed. There was histopathological confirmation of lesions as squamous cell carcinoma in 48 patients with tongue cancer. T3 and T4 cases, cases in which preoperative chemotherapy and radiation therapy were performed, and cases where biopsy was performed before imaging were excluded. The radiological DOI in US, CT, and MRI and the histopathological DOI as base were comparatively investigated and statistical analyses were performed by Bland-Altman analysis and Spearman's rank correlation coefficient. RESULTS: Bland-Altman analysis showed that the US radiological DOI was overestimated by an average of 0.2 mm compared to the histopathological DOI, while CT and MRI radiological DOI were overestimated by an average of 2-3 mm. The comparison of CT and MRI revealed that the difference between the MRI and histopathological DOI, as well as the 95% limit of agreement, were smaller than those of the CT radiological DOI. CONCLUSIONS: US is the most accurate preoperative diagnostic tool for T1 and T2 squamous cell carcinoma; CT and MRI tend to have an overestimation of about 2-3 mm and so caution is required.

Melanotic neuroectodermal tumor of infancy in the mandible: A case report.

RATIONALE: Melanocytic neuroectodermal tumor of infancy (MNTI) is a rare benign pigmented neoplasm that arises from the neural crest and has an aggressive growth pattern. It is predominantly seen in infants under 1 year of age, and the most common site of involvement is the maxilla. The currently accepted treatment is removal by surgical resection. Herein, we report a case of MNTI that involved the anterior alveolar ridge of the mandible in a 6-month-old infant. PATIENT CONCERNS: A case of a 6-month-old male child with a huge mass in the anterior alveolar ridge of the mandible. DIAGNOSIS: The tumor was diagnosed using histopathological and immunohistochemical techniques on the biopsy specimen obtained following incisional biopsy. Based on the findings, a final diagnosis of MNTI was established. INTERVENTIONS: Radical resection of the tumor was performed, after determining the extent of resection by referring to the mandibular 3D model created using the pre-operative CT data. OUTCOMES: The postoperative course was uneventful, and no recurrence has been observed to date for more than 4 years after surgery. LESSONS: This case emphasizes that early diagnosis and radical surgery are critical to the effective treatment, as MNTI exhibits rapid and destructive growth. It also requires careful and close follow-up because of high recurrence rates.

Crosstalk between oral squamous cell carcinoma cells and cancer-associated fibroblasts via the TGF-ß/SOX9 axis in cancer progression.

Cancer-associated fibroblasts (CAFs) have important roles in promoting cancer development and progression. We previously reported that high expression of sex-determining region Y (SRY)-box9 (SOX9) in oral squamous cell carcinoma (OSCC) cells was positively correlated with poor prognosis. This study developed three-dimensional (3D) in vitro models co-cultured with OSCC cells and CAFs to examine CAF-mediated cancer migration and invasion in vitro and in vivo. Moreover, we performed an immunohistochemical analysis of alpha-smooth muscle actin and SOX9 expression in surgical specimens from 65 OSCC patients. The results indicated that CAFs promote cancer migration and invasion in migration assays and 3D in vitro models. The invading OSCC cells exhibited significant SOX9 expression and changes in the expression of epithelial-mesenchymal transition (EMT) markers, suggesting that SOX9 promotes EMT. TGF-ß1 signalling inhibition reduced SOX9 expression and cancer invasion in vitro and in vivo, indicating that TGF-ß1-mediated invasion is dependent on SOX9. In surgical specimens, the presence of CAFs was correlated with SOX9 expression in the invasive cancer nests and had a significant impact on regional recurrence. These findings demonstrate that CAFs promote cancer migration and invasion via the TGF-ß/SOX9 axis.

Other iatrogenic immunodeficiency-associated lymphoproliferative disorders in the oral cavity: a clinicopathologic study of 4 cases and literature review.

OBJECTIVES: Other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OI-LPD) have been reported as one of the adverse effects of immunosuppressive therapy. The aim of this study was to describe the clinicopathologic and immunohistochemical features of OI-LPD in the oral cavity. STUDY DESIGN: Immunohistochemistry was performed to describe the immunohistochemical features in our 4 cases. The results were analyzed along with 62 cases of oral OI-LPD in the English and Japanese literature to define clinical and pathologic characteristic features. RESULTS: In our immunohistochemical analysis, Epstein-Barr virus (EBV)-positive OI-LPD showed a higher percentage of mouse double minute 2-positive cells than EBV-negative samples. A literature survey revealed that OI-LPD (including the present cases) arises primarily in the gingiva, followed by the tongue, and usually occurs with a male-to-female ratio of 1:1.9. The rate of EBV positivity was 93.8%. Further, 31 of 66 patients had osteonecrosis of the jaw and 24 of 31 patients had taken multiple immunosuppressive drugs in combination. CONCLUSIONS: We can therefore conclude that the overexpression of mouse double minute 2 in OI-LPD is associated with EBV infection, and the combination of multiple immunosuppressive drugs may be a risk factor for osteonecrosis of the jaw.

Spindle cell squamous cell carcinoma exhibiting prominent neutrophil phagocytosis: a case report.

BACKGROUND: Spindle cell squamous cell carcinoma is an uncommon variant of squamous cell carcinoma; its diagnosis is sometimes challenging because it histopathologically resembles neoplastic or reactive spindle cell lesions of mesenchymal origins. Here, we report a rare case of spindle cell squamous cell carcinoma exhibiting prominent neutrophil phagocytosis. CASE PRESENTATION: A 69-year-old Japanese man presented with pain and a polypoid mass on the lower left gingiva. He had received chemoradiotherapy for squamous cell carcinoma of the buccal mucosa 15 years prior to this consultation. In addition, he was treated for mandibular osteonecrosis 6 years after chemoradiotherapy without evidence of cancer recurrence. A biopsy revealed atypical spindle or pleomorphic cells scattered in the edematous and fibrin-rich stroma; however, no malignant squamous components were apparent. These atypical cells frequently contained neutrophils within their cytoplasm that formed cell-in-cell figures. Immunohistochemically, the atypical cells were negative for cytokeratins, epithelial membrane antigen, and E-cadherin, but positive for p63, vimentin, and p53. Although these findings suggested spindle cell squamous cell carcinoma, it was difficult to reach a definitive diagnosis. Based on a clinical diagnosis of a malignant tumor, the patient underwent a hemimandibulectomy. The surgically resected specimen had a typical spindle cell squamous cell carcinoma histology consisting of biphasic spindle cells and conventional squamous cell carcinoma components. Moreover, the surgical specimen also exhibited spindle tumor cells that frequently included neutrophils, around which intense staining for lysosomal-associated membrane protein 1 and cathepsin B was observed. This suggested that the cell-in-cell figures represent active neutrophil phagocytosis by tumor cells, and not emperipolesis. CONCLUSION: The presence of neutrophil phagocytosis may be a potent indicator of malignancy.

Central mucoepidermoid carcinoma arising directly from a glandular odontogenic cyst of the mandible: a case report.

BACKGROUND: Central mucoepidermoid carcinoma (MEC) is a rare salivary gland tumor that affects the jawbone. Glandular odontogenic cyst (GOC) is also a rare odontogenic developmental cyst with glandular differentiation. GOC shares some histological features with central MEC, and a pre-existing GOC can develop into central MEC. Here, we present a rare case of central MEC developed directly from a pre-existing GOC of the mandible. CASE PRESENTATION: A 67-year-old Japanese man presented with a cystic lesion in the right third molar region. Histologically, the biopsy specimen demonstrated both typical findings of a GOC component lined with non-keratinized squamous epithelium and a recognizable component of central MEC consisting of polycystic nests with mucous cells, intermediate cells, and epidermoid cells in the cyst wall. The results from the immunohistochemistry for cytokeratin (CK) profiling demonstrated that, while both central MEC and GOC expressed CKs 7, 14, 18, and 19, CK13 was interestingly exclusively expressed in GOC. Fluorescence in-situ hybridization (FISH) revealed the rearrangement of the Mastermind like (MAML)-2 gene in both the MEC and GOC components. CONCLUSIONS: Our case suggests that central MEC and GOC may be in the same spectrum of diseases caused by the rearrangement of the MAML-2 gene. However, given that the expression profile of CK13 was completely different between central MEC and GOC, they can be considered as separate tumors. Overall, we demonstrated a rare case in which central MEC may have originated directly from the GOC.

Identification and characterization of R2TP in the development of oral squamous cell carcinoma.

R2TP is a well-conserved molecular chaperone complex, composed of Pontin, Reptin, RPAP3, and PIH1D, in eukaryotes. Recent studies have suggested an involvement of R2TP in cancer development. However, it remains unclear if it is related to the development of oral squamous cell carcinoma (OSCC), which is the most common type of oral cancer. Here, we identify and investigate the function of R2TP in OSCC development. Immunohistochemical analysis reveals that all of the R2TP components are strongly expressed in normal oral epithelia and OSCC tissues, where actively proliferating cells are abundant. Co-immunoprecipitation assay identifies that R2TP components form a protein complex in OSCC-derived HSC4-cells. Knockdown experiments show that all R2TP components, except for RPAP3, are required for the cell proliferation and migration of HSC-4 cells. Furthermore, we reveal that Pontin contributes to a gain-of-function (GOF) activity of mutp53-R248Q in HSC-4 cells by regulating phosphorylation levels of mutp53 at Ser15 and Ser46. To our knowledge, this study is the first to report the functional involvement of R2TP and its components in the malignant characteristics of OSCC cells.

Frequent Germline and Somatic Single Nucleotide Variants in the Promoter Region of the Ribosomal RNA Gene in Japanese Lung Adenocarcinoma Patients.

Ribosomal RNA (rRNA), the most abundant non-coding RNA species, is a major component of the ribosome. Impaired ribosome biogenesis causes the dysfunction of protein synthesis and diseases called "ribosomopathies," including genetic disorders with cancer risk. However, the potential role of rRNA gene (rDNA) alterations in cancer is unknown. We investigated germline and somatic single-nucleotide variants (SNVs) in the rDNA promoter region (positions -248 to +100, relative to the transcription start site) in 82 lung adenocarcinomas (LUAC). Twenty-nine tumors (35.4%) carried germline SNVs, and eight tumors (9.8%) harbored somatic SNVs. Interestingly, the presence of germline SNVs between positions +1 and +100 (n = 12; 14.6%) was associated with significantly shorter recurrence-free survival (RFS) and overall survival (OS) by univariate analysis (p < 0.05, respectively), and was an independent prognostic factor for RFS and OS by multivariate analysis. LUAC cell line PC9, carrying rDNA promoter SNV at position +49, showed significantly higher ribosome biogenesis than H1650 cells without SNV. Upon nucleolar stress induced by actinomycin D, PC9 retained significantly higher ribosome biogenesis than H1650. These results highlight the possible functional role of SNVs at specific sites of the rDNA promoter region in ribosome biogenesis, the progression of LUAC, and their potential prognostic value.

Rac1-dependent phagocytosis of apoptotic cells by oral squamous cell carcinoma cells: A possible driving force for tumor progression.

Apoptotic cell death frequently occurs in human cancer tissues including oral squamous cell carcinoma (SCC), wherein apoptotic tumor cells are phagocytosed not only by macrophages but also by neighboring tumor cells. We previously reported that the engulfment of apoptotic SCC cells by neighboring SCC cells frequently occurs at the invading front. Therefore, we hypothesized that the phagocytosis of these apoptotic cells by tumor cells contributes to disease progression. Herein, using cultured oral SCC cells, we aimed to confirm whether tumor cells actually phagocytose apoptotic cells and to examine whether cellular activities are regulated by the phagocytosis of apoptotic cells. Co-culture experiments showed that living cells could ingest apoptotic cells into phagolysosomes. NSC23766, an inhibitor of Rac1, which is a key regulator of phagocytic cup formation in professional phagocytes, dramatically suppressed the phagocytosis of apoptotic cells by living cells. Additionally, cell migration and the secretion of DKK1, a tumor-promoting protein, were enhanced by co-culture with apoptotic cells, whereas NSC23766 inhibited these effects. These results show that tumor cells can actively phagocytose apoptotic neighbors in a Rac1-dependent manner and that such activity increases their migration. The regulation of apoptotic cell phagocytosis thus represents new directions for therapeutic intervention for oral cancer.

Cytoplasmic expression of SOX9 as a poor prognostic factor for oral squamous cell carcinoma.

Transcription factor SRY­box 9 (SOX9) is a key regulator of chondrocyte differentiation and sex determination, and it is also involved in the progression of various types of human cancer. However, its putative association with oral squamous cell carcinoma (OSCC) remains elusive. The aim of the present study was to investigate the expression profiles of SOX9 in various oral epithelial lesions, including OSCC. We performed immunohistochemical analysis of SOX9 expression in surgical specimens of OSCC, which simultaneously exhibited different grades of epithelial lesions, and analyzed the correlation between SOX9 expression and several clinicopathological factors. Moreover, we performed immunofluorescent staining, western blot analysis and real­time reverse transcription­polymerase chain reaction to assess SOX9 expression in OSCC HSC­3 (a metastatic cell line) and HSC­4 (a non­metastatic cell line) cell lines. In surgical specimens, SOX9 expression was detected in the nuclei of proliferating cells in areas with epithelial dysplasia and carcinoma in situ, but not in areas with normal epithelia. Nuclear SOX9 expression was observed in most SCC cells. Notably, cytoplasmic SOX9 expression was confirmed only in some SCC cells; however, cytoplasmic SOX9 expression was significantly and positively correlated with poor clinical outcomes. Both protein and mRNA expression of SOX9 were significantly higher in the HSC­3 cell line than that in the HSC­4 line. Notably, however, only HSC­3 cells exhibited cytoplasmic localization of SOX9 expression. Our findings indicate that SOX9 may be involved in the tumorigenesis and progression of OSCC. Furthermore, its cytoplasmic expression represents a potential predictive biomarker for tumor aggressiveness and OSCC prognosis.

Inflammatory Myofibroblastic Tumor Mimicking Apical Periodontitis.

Inflammatory myofibroblastic tumors (IMTs) are rare. IMTs of the head and neck occur in all age groups, from neonates to old age, with the highest incidence occurring in childhood and early adulthood. An IMT has been defined as a histologically distinctive lesion of uncertain behavior. This article describes an unusual case of IMT mimicking apical periodontitis in the mandible of a 42-year-old man. At first presentation, the patient showed spontaneous pain and percussion pain at teeth #28 to 30, which continued after initial endodontic treatment. Panoramic radiography revealed a radiolucent lesion at the site. Cone-beam computed tomographic imaging showed osteolytic lesions, suggesting an aggressive neoplasm requiring incisional biopsy. Histopathological examination indicated an IMT. The lesion was removed en bloc under general anesthesia, and the patient manifested no clinical evidence of recurrence for 24 months. Lesions of nonendodontic origin should be included in the differential diagnosis of apical periodontitis. Every available diagnostic tool should be used to confirm the diagnosis. Cone-beam computed tomographic imaging is very helpful for differential diagnosis in IMTs mimicking apical periodontitis.