Vitamin D-metabolizing enzyme CYP24A1 affects oncogenic behaviors of oral squamous cell carcinoma and its prognostic implication.

Vitamin D is an essential molecule for cellular homeostasis, playing a critical role in cell fate decisions including cell proliferation, differentiation, and viability. Accumulating evidence has revealed that expression of the vitamin D-metabolizing enzyme CYP24A1 is dysregulated in different types of human malignancy. CYP24A1 has been shown to be involved in the oncogenic property of a variety of carcinoma cells. However, the pathological relevance of CYP24A1 expression level in human oral malignancy remains to be clarified. In the present study, suppression of CYP24A1 expression in oral squamous cell carcinoma (OSCC) cells increased cell proliferation, invasive activity, colony formation efficacy, and tumor growth in vivo. In addition, knockout of CYP24A1 expression inhibited cell death induced by two different types of anticancer drugs, i.e., fluorouracil and cisplatin. Gene clustering by RNA-sequence analysis revealed that several signaling molecules associated with MYC are involved in CYP24A1-mediated oncogenic behaviors. Furthermore, decreased expression level of CYP24A1 was observed in 124/204 cases (61%) of OSCC and was shown to be associated with short relapse-free and overall survival periods. The results showed that a low expression level of CYP24A1 promotes the oncogenic activity of OSCC and is significantly associated with poor prognosis in patients with this malignancy.

Exploring olfactory receptor family 7 subfamily C member 1 as a novel oral cancer stem cell target for immunotherapy.

The mortality rate of oral cancer has not improved over the past three decades despite remarkable advances in cancer therapies. Oral cancers contain a subpopulation of cancer stem cells (CSCs) that share characteristics associated with normal stem cells, including self-renewal and multi-differentiation potential. CSCs are tumorigenic, play a critical role in cancer infiltration, recurrence, and distant metastasis, and significantly contribute to drug resistance to current therapeutic strategies, including immunotherapy. Cytotoxic CD8+ T lymphocytes (CTLs) are key immune cells that effectively recognize peptide antigens presented by the major histocompatibility complex class I molecules. Increasing evidence suggests that cancer antigen-specific targeting by CTLs effectively regulates CSCs that drive cancer progression. In this study, we utilized data from public domains and performed various bioassays on human oral squamous cell carcinoma clinical samples and cell lines, including HSC-2 and HSC-3, to investigate the potential role of olfactory receptor family 7 subfamily C member 1 (OR7C1), a seven transmembrane G-protein-coupled olfactory receptor that is also expressed in nonolfactory tissues and was previously reported as a novel marker and target of colon cancer initiating cell-targeted immunotherapy, in CSC-targeted treatment against oral cancer. We found that the OR7C1 gene was expressed only in oral CSCs, and that CTLs reacted with human leukocyte antigen-A24-restricted OR7C1 oral CSC-specific peptides. Taken together, our findings suggest that OR7C1 represents a novel target for potent CSC-targeted immunotherapy in oral cancer.

Senescence-associated secretory phenotypes in mesenchymal cells contribute to cytotoxic immune response in oral lichen planus.

Oral lichen planus is a chronic inflammatory condition that adversely affects the oral mucosa; however, its etiology remains elusive. Consequently, therapeutic interventions for oral lichen planus are limited to symptomatic management. This study provides evidence of the accumulation of senescent mesenchymal cells, CD8 + T cells, and natural killer cells in patients with oral lichen planus. We profiled the patients' tissues using the National Center for Biotechnology Information Gene Expression Omnibus database and found that senescence-related genes were upregulated in these tissues by gene set enrichment analysis. Immunohistochemical analysis showed increased senescent mesenchymal cells in the subepithelial layer of patients with oral lichen planus. Single-cell RNA-seq data retrieved from the Gene Expression Omnibus database of patients with oral lichen planus revealed that mesenchymal cells were marked by the upregulation of senescence-related genes. Cell-cell communication analysis using CellChat showed that senescent mesenchymal cells significantly influenced CD8 + T cells and natural killer cells via CXCL12-CXCR4 signaling, which is known to activate and recruit CD8 + T cells and NK cells. Finally, in vitro assays demonstrated that the secretion of senescence-associated factors from mesenchymal cells stimulated the activation of T cells and natural killer cells and promoted epithelial cell senescence and cytotoxicity. These findings suggest that the accumulation of mesenchymal cells with senescence-associated secretory phenotype may be a key driver of oral lichen planus pathogenesis.

Immunohistological evaluation of patients treated with intra-arterial chemoradiotherapy and surgery for oral cancer.

Preoperative intra-arterial chemoradiotherapy (IACRT) can improve the outcome and reduce the extent of surgery in patients with advanced oral cancer. However, the response to this regimen varies among patients, which may be related to the immune status of the tumor. We investigated the effects of proteins involved in tumor immunity on the outcomes of combined IACRT and surgery for oral cancer. We examined CD8 + and FoxP3 + tumor-infiltrating lymphocytes (TILs) and programmed death ligand 1 (PD-L1) expression on immune cells and tumor cells in pretreatment biopsy samples from 69 patients diagnosed with oral cancer treated with IACRT at our institution during 2000-2020. Patients with abundant CD8 + TILs had significantly better 5-year disease-specific survival (DSS) compared to that of patients with less infiltration of these cells (P = 0.016). Patients with higher FoxP3 + T-cells invasion had significantly better DSS compared to that of less FoxP3 (P = 0.005). Patients with high PD-L1 expression in tumor cells and immune cells had significantly better DSS than that of patients with low PD-L1 expression in these cells (P = 0.009 and P = 0.025, respectively). Collectively, these results suggest that the tumor immune microenvironment could affect outcomes of IACRT treatment in oral cancer.

Multicenter retrospective study of nivolumab for recurrent/metastatic oral squamous cell carcinoma.

OBJECTIVES: Immunotherapy with nivolumab for patients with recurrent/metastatic oral squamous cell carcinoma has not been evaluated. Here, we aimed to examine the efficacy, safety, and prognostic factors of nivolumab in these patients. MATERIALS AND METHODS: This multicenter retrospective observational study involved patients who received nivolumab between April 2017 and June 2019. The patient characteristics were evaluated for association with progression-free and overall survival. Progression-free and overall survival rates were calculated; parameters that were significant in the univariate analysis were used as explanatory variables. Independent factors for progression-free and overall survival were identified using multivariate analysis. RESULTS: Totally, 143 patients were included. The overall response and disease control rates were 27.3% and 46.2%, respectively. The median, 1- and 2-year progression-free survival rates were 2.7 months, 25.4%, and 19.2%, respectively; those for overall survival were 11.2 months, 47.3%, and 33.6%, respectively. The independent factors affecting progression-free survival were performance status and immune-related adverse event occurrence, whereas those affecting overall survival were performance status, target disease, and number of previous lines of systemic cancer therapy. Eight patients reported grade ≥3 immune-related adverse events. CONCLUSION: Nivolumab was effective for recurrent/metastatic oral squamous cell carcinoma treatment and was well tolerated by patients.

Injectate spread in ultrasound-guided inferior alveolar nerve block: a cadaveric study.

PURPOSE: Ultrasound-guided inferior alveolar nerve block (UGIANB) is a mandibular analgesic procedure in which local anesthetic is injected into the pterygomandibular space (PMS). Several studies have reported the clinical efficacy of UGIANB for mandibular surgeries; however, its effective range has never been investigated. We performed a cadaveric study to investigate the success rate of UGIANB injections and to determine whether injected dye could stain the mandibular nerve (MN) trunk and its branches. METHODS: We performed UGIANB on the bilateral faces of 4 Thiel-embalmed cadavers. A needle was advanced to the PMS under ultrasound guidance and 5 mL of dye was injected. The cadaver was dissected and inspected for the presence of dye in the PMS; the range of dye spread to any of the inferior alveolar nerve (IAN), lingual nerve (LN), buccal nerve (BN), mandibular nerve (MN), auriculotemporal nerve (ATN), or facial nerves; and for the presence of intravascular dye. RESULTS: We performed eight UGIANB procedures on four cadavers. Dye was observed in the PMS in 7/8 injections. Staining was observed in all IAN, LN, and BNs that could be identified at dissection. No MN or auriculotemporal nerves (ATNs) were stained in any injections. No intravascular dye was observed in any injections. CONCLUSIONS: UGIANB can administer anesthetic into the PMS with high accuracy. UGIANB injections reached the IAN, LN, and BNs, but did not reach the MN or ATNs located outside the PMS. The findings of this cadaveric study indicate that UGIANB can provide sufficient analgesia for mandibular surgeries.

Antiresorptive agent-related osteonecrosis of the jaw (ARONJ) in urological malignancies: a multi-center retrospective study.

INTRODUCTION: We evaluated the incidence and risk factors for antiresorptive agent-related osteonecrosis of the jaw (ARONJ) in prostate and kidney cancer patients. MATERIALS AND METHODS: We retrospectively reviewed the clinical data of 547 patients from 13 hospitals. Prostate and kidney cancer patients with bone metastases who were treated with a bone-modifying agent (BMA) between January 2012 and February 2019 were enrolled. Exclusion criteria were BMA use for hypercalcemia, a lack of clinical data, a follow-up period of less than 28 days and a lack of evaluation by dentists before BMA administration. The diagnosis and staging of ARONJ were done by dentists. RESULTS: Two-hundred eighteen patients were finally enrolled in the study, including 168 prostate cancer patients and 50 kidney cancer patients. Of them, 49 (29%) prostate cancer patients and 18 (36%) kidney cancer patients needed tooth extraction prior to BMA initiation. The mean follow-up period after BMA initiation was 552.9 ± 424.7 days (mean ± SD). In the cohort, 23% of the patients were diagnosed with ARONJ in the follow-up period. The 1-year cumulative incidences of ARONJ were 9.4% and 15.4% in prostate and kidney cancer patients, respectively. Multivariate analysis indicated that kidney cancer, tooth extraction before BMA and a body mass index (BMI) ≥ 25 kg/m2 were significant predictors for ARONJ. CONCLUSION: ARONJ is not a rare adverse event in urological malignancies. Especially, kidney cancer, high BMI patients and who needed tooth extraction before BMA were high risk for developing ARONJ.

Prognostic value of HLA class I expression in patients with oral squamous cell carcinoma.

Human leukocyte antigen (HLA) class Ⅰ molecules play a central role in anticancer immunity, but their prognostic value in oral squamous cell carcinoma (OSCC) remains unclear. We examined HLA class I expression in 2 distinct tumor compartments, namely, the tumor center and invasive front, and evaluated the association between its expression pattern and histopathological status in 137 cases with OSCC. Human leukocyte antigen class Ⅰ expression was graded semiquantitatively as high, low, and negative. At the invasive front of the tumor, HLA class I expression was high in 72 cases (52.6%), low in 44 cases (32.1%), and negative in 21 cases (15.3%). The HLA class I expression in the tumor center was high in 48 cases (35.0%), low in 58 cases (42.4%), and negative in 31 cases (22.6%). The 5-year overall survival and disease-specific survival rates were good in cases with high HLA class I expression at the invasive front; however, there was no significant difference in survival based on HLA class I expression in the tumor center. In addition, high HLA class I expression was correlated with high CD8+ T cell density, whereas negative HLA class I expression was correlated with low CD8+ T cell density at the invasive front. These results suggest that it is easier for CD8+ T cells to recognize presented peptides in the case of high HLA class Ⅰ expression at the tumor invasive front and could be a prognostic factor for OSCC.

Quantitative Evaluation of Cephalometric Radiographs of Patients With Hemifacial Microsomia.

OBJECTIVE: To clarify the morphological characteristics of hemifacial microsomia (HFM) by quantitative analysis of cephalometric radiographs. DESIGN: Retrospective study of imaging data. SETTING: Imaging data were obtained from the records of Sapporo Medical University Hospital. PATIENTS: A total of 183 patients with HFM. MAIN OUTCOME MEASURES: We used linear and angular measurements and analyzed the middle face and lower face. RESULTS: The ratios of the affected side to the unaffected (A/U) side of the lateral distance of the mandibular condyle, the mandibular ramus height, and the length of the body of the mandible in the HFM group were significantly lower than in the control group. The inclination of the body of the mandible was significantly larger in the side with HFM than in the unaffected side, and the extent of the mandibular ramus was significantly lower than in the unaffected side. The A/U ratios of the extent of the angle of the mandible and the inclination of the body of the mandible in the HFM group were larger than in the control group. Moreover, the length and the inclination of the body of the mandible had significant correlations with the distance of the shift of the menton. CONCLUSIONS: It is suggested that improving the hypoplasia of the length of the body of the mandible and the extent of the angle of the mandible on the affected side will lead to more effective treatment of jaw deformity in patients with HFM.

Diverticulum of the buccal mucosa: a rare case report and review of the literature.

BACKGROUND: Cases of diverticula of the buccal mucosa are extremely rare. Literature searches of databases such as PubMed/MEDLINE for this condition have revealed only 10 case reports. In this case report, we describe our experience in the management of this rare condition and review the previous 10 previously reported cases. CASE PRESENTATION: A 66-year-old man presented with a pouch containing inspissated food debris located posterior to the papilla of the parotid duct in his left buccal mucosa. The diagnosis of a diverticulum arising from the buccal mucosa was confirmed based on clinical and radiographic findings. Gross examination of the locally resected tissue specimen revealed a pouch measuring 14 mm in diameter and 8 mm in depth, that was whitish in color and had an elastic, soft, and smooth surface. Microscopic examination revealed a cyst-like lesion lined by stratified squamous epithelium and granulation tissue, with a chronic inflammatory infiltration in the peripheral stromal tissue of the epithelial layer. After surgical excision of the lesion, there was no recurrence during the follow-up period of 5 years and 10 months. CONCLUSIONS: We have presented a rare case of a diverticulum of the buccal mucosa. This is the first report of a case confirmed not only by the clinicopathological findings, but also by computed tomography and magnetic resonance imaging findings. From the magnetic resonance imaging and intraoperative findings, we inferred that the diverticulum was caused by an idiopathic developmental anomaly due to a partial defect of the buccinator muscle.

Microenvironmental stresses induce HLA-E/Qa-1 surface expression and thereby reduce CD8(+) T-cell recognition of stressed cells.

Hypoxia and glucose deprivation are often observed in the microenvironment surrounding solid tumors in vivo. However, how they interfere with MHC class I antigen processing and CD8(+) T-cell responses remains unclear. In this study, we analyzed the production of antigenic peptides presented by classical MHC class I in mice, and showed that it is quantitatively decreased in the cells exposed to either hypoxia or glucose deprivation. In addition, we unexpectedly found increased surface expression of HLA-E in human and Qa-1 in mouse tumor cells exposed to combined oxygen and glucose deprivation. The induced Qa-1 on the stressed tumor model interacted with an inhibitory NKG2/CD94 receptor on activated CD8(+) T cells and attenuated their specific response to the antigen. Our results thus suggest that microenvironmental stresses modulate not only classical but also nonclassical MHC class I presentation, and confer the stressed cells the capability to escape from the CD8(+) T-cell recognition.

Additive effect of radiosensitization by 2-deoxy-D-glucose delays DNA repair kinetics and suppresses cell proliferation in oral squamous cell carcinoma.

BACKGROUND: It has well known that, compared to normal cells, tumor cells have a different manner of energy metabolism, which influences the sensitivity of radiotherapy. However, whether inhibition of glycolysis enhances the efficacy of radiotherapy is a matter of debate in oral squamous cell carcinoma (OSCC). The aim of this study was to characterize whether the combination of radiotherapy with the glucose inhibitor 2-deoxy-D-glucose (2-DG) affected DNA repair kinetics. METHODS: To compare the synergistic effect of 2-DG, we examined the cell survival after treatment with radiation, 2-DG, and a combination of the two in five OSCC cell lines and one lip fibroblast cell line, determined using clonogenic survival assay. Changes in the protein levels of DNA repair kinetics such as PARP, Rad51, and Ku-70 were analyzed by Western blotting. Then, using one of the five OSCC cell lines, we assessed the inhibition of xenograft tumor growth in vivo. RESULTS: We found that 2-DG with radiation induced significant inhibition of cell proliferation in cell line SAS (P<.01, one-way ANOVA). Radiation treatment was associated with decreased expression of the DNA repair markers. In additional, combinational treatment with 2-DG and radiation significantly inhibited the xenograft tumor growth compared to the control (P<.05), and treatment with 2-DG or radiation alone. CONCLUSIONS: Our study suggests that 2-DG has synergistic cytotoxic effects when combined with radiotherapy, which might lead to the design of an effective metabolic target therapy in vitro and in vivo.

Relationship Between Mandibular Ramus Height and Masticatory Muscle Function in Patients With Unilateral Hemifacial Microsomia.

OBJECTIVE: To clarify the relationship between mandibular ramus height and function of masticatory muscles in patients with hemifacial microsomia. DESIGN: Retrospective study of imaging and physiological data. SETTING: Images and physiological data were obtained from the records of Sapporo Medical University Hospital. PATIENTS: A total of 29 patients with hemifacial microsomia who showed Pruzansky grades I, II deformity. MAIN OUTCOME MEASURES: Mandibular ramus height and masticatory muscle volume were evaluated with multi-detector row computed tomography. The electromyographic value was measured by the K7 Evaluation System. The hemifacial microsomia patients were classified into three groups based on the mandibular ramus height ratio of the affected and unaffected sides: group 0, >1.00; group 1, 1.00 to 0.85; group 2, <0.85. The Tukey-Kramer method and Games-Howell method were used to determine correlations between parameters. RESULTS: Decreased mandibular ramus height was significantly correlated with both reduced electromyographic values of the masseter muscle (P < .05) and the amount of mandibular lateral deviation at the time of maximum opening (P < .05) on the affected side. These differences were prominent in unilateral hemifacial microsomia patients classified as group 2. CONCLUSIONS: Decreased mandibular ramus height may cause dysfunction of the masseter muscles but not the temporal muscle on the affected side in patients with hemifacial microsomia.

Six-transmembrane epithelial antigen of the prostate-1 plays a role for in vivo tumor growth via intercellular communication.

Six-transmembrane epithelial antigen of the prostate-1 (STEAP-1) is a novel cell surface protein overexpressed only in the prostate among normal tissues and various types of cancer including prostate, bladder, lung, and ovarian cancer. Although its function in prostate and tumor cells has been remained unclear, due to its unique and restricted expression, STEAP-1 is expected to be an attractive target for cancer therapy. Here, we show that knockdown of STEAP-1 in human cancer cells caused the retardation of tumor growth compared with wild type in vivo. In contrast, STEAP-1 introduced tumor cells augmented the tumor growth compared with STEAP-1-negative wild type cells. Using dye transfer assay, we demonstrate that the STEAP-1 is involved in intercellular communication between tumor cells and adjacent tumor stromal cells and therefore may play a key role for the tumor growth in vivo. These data indicate the inhibition of the STEAP-1 function or expression can be a new strategy for cancer therapy.

Macroscopic and microscopic features of the mandibular condyle in autopsied elderly individuals.

Many studies have attempted to classify the macroscopic shapes of the mandibular condyle in humans; however, no consensus has yet been reached because the shapes vary. One problem is that classification of macroscopic morphological changes of the condylar surface has been largely based on bones from ancient people, with few bones from modern people covering many different age groups. In this study, 144 condyles from 78 cadavers (40 men, 38 women; age at death: >70 years) were investigated. The macroscopic shapes of the condyles were classified from posterior and lateral views into four types: convex, flattened, angled, and irregular. Of the 144 condyles, 25 were investigated microscopically. On macroscopic examination, in both posterior and lateral views, convex-type condyles were most frequently observed. Most posterior convex-type condyles were also categorized as the lateral convex type. On histological examination, we observed an increase in cartilage cells (7 condyles, 28%), a decrease in cartilage cells (3 condyles, 12%). Increases in cartilage cells were seen only in angled and irregular types (P = 0.001), whereas decreases in cartilage cells were only observed in the flattened type (P = 0.01). A convex macroscopic form appears to be standard for human mandibular condyles, even in the elderly. The histological findings suggest that mandibular condyles tend to not only undergo flattening, but also undergo progressive changes toward protrusion with age due to increased numbers of cartilage cells. In other words, this study suggests that there is potential for progressive alterations in mandibular condyles in the elderly.

Application of Single Cell Type-Derived Spheroids Generated by Using a Hanging Drop Culture Technique in Various In Vitro Disease Models: A Narrow Review.

Cell culture methods are indispensable strategies for studies in biological sciences and for drug discovery and testing. Most cell cultures have been developed using two-dimensional (2D) culture methods, but three-dimensional (3D) culture techniques enable the establishment of in vitro models that replicate various pathogenic conditions and they provide valuable insights into the pathophysiology of various diseases as well as more precise results in tests for drug efficacy. However, one difficulty in the use of 3D cultures is selection of the appropriate 3D cell culture technique for the study purpose among the various techniques ranging from the simplest single cell type-derived spheroid culture to the more sophisticated organoid cultures. In the simplest single cell type-derived spheroid cultures, there are also various scaffold-assisted methods such as hydrogel-assisted cultures, biofilm-assisted cultures, particle-assisted cultures, and magnet particle-assisted cultures, as well as non-assisted methods, such as static suspension cultures, floating cultures, and hanging drop cultures. Since each method can be differently influenced by various factors such as gravity force, buoyant force, centrifugal force, and magnetic force, in addition to non-physiological scaffolds, each method has its own advantages and disadvantages, and the methods have different suitable applications. We have been focusing on the use of a hanging drop culture method for modeling various non-cancerous and cancerous diseases because this technique is affected only by gravity force and buoyant force and is thus the simplest method among the various single cell type-derived spheroid culture methods. We have found that the biological natures of spheroids generated even by the simplest method of hanging drop cultures are completely different from those of 2D cultured cells. In this review, we focus on the biological aspects of single cell type-derived spheroid culture and its applications in in vitro models for various diseases.

Notch signaling genes and CD8+ T-cell dynamics: Their contribution to immune-checkpoint inhibitor therapy in oral squamous cell carcinoma: A retrospective study.

BACKGROUND: Aberrant Notch signaling pathway has been related with the tumorigenesis in head and neck region, involving oral cavity. Here, we report the correlation between mutations in the Notch signaling pathway and CD8+ T-cell infiltration via PD-L1, which lead to enhanced antitumor immunity and may target for immune-checkpoint inhibitors (ICIs) therapy. METHODS: This retrospective study analyzed the results of immunohistochemical staining for PD-L1 and CD8+ T-cell infiltration in 10 patients and whole-exome sequencing (WES) was conducted on five of these patients to identify frequently mutated genes. RESULTS: Four of 10 patients were positive for PD-L1 and CD8+ T. By analyzing WES in three of these four patients, we notably identified the mutations of NOTCH1, FBXW7, and noncoding RNA intronic mutation in NOTCH2NLR in two of these three patients. This study may enable better selection of ICI therapy with CD8+ T-cell infiltration via PD-L1 expression for oral squamous cell carcinoma patients with mutations in Notch signaling pathway.

Small proline-rich protein-1B is overexpressed in human oral squamous cell cancer stem-like cells and is related to their growth through activation of MAP kinase signal.

Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are considered to be essential for tumor maintenance, recurrence and metastasis. Therefore, eradication of CSCs/CICs is essential to cure cancers. However, the molecular mechanisms of CSCs/CICs are still elusive. In this study, we investigated the molecular mechanism of the cell growth of oral CSCs/CICs. Oral CSCs/CICs were isolated as aldehyde dehydrogenase 1 bright (ALDH1(br)) cells by the ALDEFLUOR assay. Small proline-rich protein-1B (SPRR1B) gene was shown to be overexpressed in ALDH1(br) cells by a cDNA microarray and RT-PCR. SPRR1B was shown to have a role in cell growth and maintenance of ALDH1(br) cells by SPRR1B overexpression and knockdown experiments. To elucidate the molecular mechanism by which SPRR1B regulates cell growth, further cDNA microarray analysis was performed using SPRR1B-overexpressed cells and cells with SPRR1B knocked down by siRNA. Expression of the tumor suppressor gene Ras association domain family member 4 (RASSF4) was found to be suppressed in SPRR1B-overexpressed cells. On the other hand, the expression of RASSF4 was enhanced in cells in which SPRR1B expression was knocked down by SPRR1B-specific siRNA. RASSF4 has an RA (Ras association) domain, and we thus hypothesized that RASSF4 modulates the MAP kinase signal downstream of the Ras signal. MAP kinase signal was activated in SPRR1B-overexpressed cells, whereas the signal was suppressed in SPRR1B knocked down cells. Taken together, the results indicate that the expression of SPRR1B is upregulated in oral CSCs/CICs and that SPRR1B has a role in cell growth by suppression of RASSF4.

Silencing of GLUT-1 inhibits sensitization of oral cancer cells to cisplatin during hypoxia.

BACKGROUND: During tumor development, cells are exposed to a hypoxic microenvironment. Tumor hypoxia also has a profound influence on the sensitivity of cancer chemotherapy. The objective of this study was to investigate the mechanism of cisplatin (CDDP) resistance of oral squamous cell carcinoma (OSCC) cells under hypoxia by analyzing gene expression profiles to identify key genes and factors involved. METHODS: Cell viability was measured following culture of the cells in the presence or absence of CDDP, under normoxic or hypoxic conditions, using a CCK-8 assay. Analysis of the expression of HIF target genes in hypoxia-treated cells was performed using an HIF-regulated cDNA plate array. Changes in the mRNA expression of selected HIF target genes were analyzed using RT-PCR, and changes in the protein levels of these genes were analyzed by Western blotting. Tumor cell apoptosis was assessed by flow cytometry. RESULTS: The OSCC cell lines responded differently to CDDP under normoxic and hypoxic conditions. The expression of glucose transporter protein-1 (GLUT-1) was up-regulated in human squamous cell carcinoma of mouth (HSC-2) cells under hypoxia. Furthermore, there was little correlation between the cisplatin sensitivity of human squamous cell carcinoma of tongue (SAS) in normoxia and hypoxia. After GLUT-1 knockdown, CDDP treatment resulted in increased rates of apoptosis under hypoxia as compared with normoxia in cell lines HSC-2, Ca9-22, and SAS (P = 0.025). CONCLUSION: The results of this study suggest that knockdown of GLUT-1 inhibits sensitization of oral squamous cells to CDDP during hypoxia in HSC-2, Ca9-22, and SAS cells.

A rare case report of diverticulum of the buccal mucosa.

We report a case of diverticulum of the buccal mucosa. A 56-year-old man had a small pouch-shaped lesion behind the parotid papilla that caused pain and food impaction. After resection, the lesion was histopathologically diagnosed as diverticulum without buccal muscle tear. There has been no recurrence during 1 year postoperatively.