Keiji Shinozuka

MicroRNA-125b regulates proliferation and radioresistance of oral squamous cell carcinoma.

Background:MicroRNAs (miRNAs) are involved in essential biological activities, and have been reported to exhibit differential expression profiles in various cancers. Our previous study demonstrated that intercellular adhesion molecule-2 (ICAM2) inhibition induces radiosensitisation in oral squamous cell carcinoma (OSCC) cells. Thus, we hypothesised that certain miRNAs play crucial roles in radioresistance in OSCC by regulating ICAM2 expression.Methods:Because predicted target gene analyses revealed that microRNA-125b (miR-125b) potentially regulates ICAM2 mRNA expression, we examined the association between miR-125b and radioresistance. The expression of miR-125b was investigated by real-time quantitative reverse transcriptase–PCR. For a functional analysis, miR-125b was transfected to OSCC-derived cells.Results:A downregulated expression of miR-125b was found in OSCC-derived cell lines and OSCC samples. The miR-125b-transfected cells showed a decreased proliferation rate, enhanced radiosensitivity to X-ray irradiation and diminished ICAM2 mRNA expression. Moreover, miR-125b expression correlated with OSCC tumour staging and survival.Conclusion:These findings suggested that the downregulated miR-125b expression was associated with proliferation and radioresistance mechanisms, probably through ICAM2 signalling. Thus, controlling the expression or activity of miR-125b might contribute to suppressing proliferation and overcoming radioresistance in OSCC.

Identification of cisplatin-resistance related genes in head and neck squamous cell carcinoma.

Resistance to cisplatin is a major obstacle to successful treatment of head and neck squamous cell carcinoma (HNSCC). To investigate the molecular mechanism of this resistance, we compared the gene expression profiles between the cisplatin‐sensitive SCC cell lines (Sa‐3, H‐1 and KB) and the cisplatin‐resistant cell lines established from them (Sa‐3R, H‐1R and KB‐R) using Affymetrix U133 Plus 2.0 microarray. We identified 199 genes differentially expressed in each group. To identify important functional networks and ontologies to cisplatin resistance, the 199 genes were analyzed using the Ingenuity Pathway Analysis Tool. Fifty‐one of these genes were mapped to genetic networks, and we validated the top‐10 upregulated genes by real‐time reverse transcriptase‐polymerase chain reaction. Five novel genes, LUM, PDE3B, PDGF‐C, NRG1 and PKD2, showed excellent concordance with the microarray data. In 48 patients with oral SCC (OSCC), positive immunohistochemical staining for the five genes correlated with chemoresistance to cisplatin‐based combination chemotherapy. In addition, the expression of the five genes predicted the patient outcomes with chemotherapy. Furthermore, siRNA‐directed suppressed expression of the five genes resulted in enhanced susceptibility to cisplatin‐mediated apoptosis. These results suggested that these five novel genes have great potential for predicting the efficacy of cisplatin‐based chemotherapy against OSCC. Global gene analysis of cisplatin‐resistant cell lines may provide new insights into the mechanisms underlying clinical cisplatin resistance and improve the efficacy of chemotherapy for human HNSCC.

Real-time tissue elastography for the diagnosis of lymph node metastasis in oral squamous cell carcinoma.

We compared conventional ultrasound (US) B-mode, color Doppler and elastographic assessment of lymph node (LN) stiffness against pathological findings from surgical samples, to determine the most useful factors for identifying LN metastases. Seventy-one LNs in 19 patients with oral squamous cell carcinoma (OSCC) were examined. Using our new system, elastography images were scored from 1-5. The score 1-4 were correlated with the blue area of each LN, which indicated increased stiffness: (1) none; (2) < 50%; (3) 50%; or (4) > 50%. A score 5 indicated central necrosis and did not correlate with the blue area. We found significant differences in minimal diameter, shape index, margin, internal structure, hilus presence or absence, elastography score and percentage of blue area between metastatic and nonmetastatic LNs. Stepwise regression analysis identified elastography score 3-5 as an independent significant LN metastatic factor, suggesting that our scoring system may be useful for accurately diagnosing metastatic LNs.

Targeting fibroblast growth factor receptor 3 enhances radiosensitivity in human squamous cancer cells.

Conventional therapies including radiation therapy cannot cure squamous cell carcinoma (SCC), and new treatments are clearly required. Our recent studies have shown that SCC cell lines exhibiting radioresistance show significant upregulation of the fibroblast growth factor receptor 3 (FGFR3) gene. We hypothesized that inhibiting FGFR3 would suppress tumor cell radioresistance and provide a new treatment approach for human SCCs. In the present study, we found that RNA interference-mediated FGFR3 depletion in HSC-2 cells, a radioresistant cell line, induced radiosensitivity and inhibited tumor growth. Use of an FGFR3 inhibitor (PD173074) obtained similar results with suppression of the autophosphorylation extracellular signal-regulated kinase pathway in HSC-2 cells and lung cancer cell lines. Moreover, the antitumor growth effect of the combination of PD173074 and radiation in vivo was also greater than that with either drug alone or radiation alone. Our results provided novel information on which to base further mechanistic study of radiosensitization by inhibiting FGFR3 in human SCC cells and for developing strategies to improve outcomes with concurrent radiotherapy.

Lipocalin-2 is associated with radioresistance in oral cancer and lung cancer cells.

The aim of the present study was to identify a target molecule that could predict the efficacy of radiotherapy in oral squamous cell carcinoma (OSCC). We used DNA microarray analysis to identify differences in gene expression after X-ray irradiation. We compared the gene expression profiles between X-ray (8 Gy)-irradiated Ca9-22 cells (an OSCC-derived cell line) and unirradiated Ca9-22 cells. A total of 167 genes with a 2-fold higher level of expression induced by X-ray irradiation were identified. Lipocalin-2 (LCN2) had the greatest increase in expression after X-ray irradiation, and it was categorized in a network that has cancer-related functions with the Ingenuity Pathway Analysis tool. Upregulated expression of LCN2 mRNA was validated by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis. When the LCN2 gene was knocked down in OSCC cells (Ca9-22 and HSC-2) and lung cancer cells (A549) by using small interfering RNA, the radiosensitivity of these cells was enhanced. Our findings suggest that the overexpression of LCN2 is likely associated with radioresistance in oral cancer and lung cancer cells, and that LCN2 expression levels could be used to predict radioresistance. Thus, regulating the expression or function of LCN2 could enhance the radiation response, resulting in a favorable outcome of radiotherapy.

Oncolytic activity of Sindbis virus in human oral squamous carcinoma cells.

Background:Sindbis virus (SIN) infection causes no or only mild symptoms (fever, rash, and arthralgia) in humans. However, SIN has a strong cytopathic effect (CPE) on various cancer cells. This study focuses on the oncolytic activity of SIN AR399 on oral cancer cells compared with reovirus, a well-known oncolytic virus that targets cancer cells.Methods:We analysed the cytotoxicity and growth of SIN in 13 oral squamous cell carcinoma (OSCC) cell lines (HSC-2, HSC-3, HSC-4, Ca9-22, H-1, Sa-3, KON, KOSC-2, OK-92, HO-1-N1, SCC-4, SAT, SKN-3) and normal human oral keratinocytes (NHOKs).Results:Sindbis virus infection induced CPE in 12 OSCC cell lines at a low multiplicity of infection (MOI) of 0.01, but not in the OSCC cell line, HSC-4 or NHOKs. Sindbis viral growth was not observed in NHOKs, whereas high SIN growth was observed in all OSCC cell lines, including HCS-4. The cytotoxicity and growth of SIN was the same as reovirus at an MOI of 20 in 12 OSCC cell lines. The CPE was shown, by terminal deoxyribonucleotidyl transferase–mediated dUTP nick-end labelling assays, to be apoptotic cell death. Furthermore, quantitative RT-PCR of mRNA in HSC-3 and HSC-4 cells after SIN infection showed that activation of caspases, cytochrome c, and IκBα was associated with SIN-induced apoptosis.Conclusion:As a replication-competent oncolytic virus, SIN may be a useful therapeutic modality for oral cancers.

Downregulation of Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 in Oral Squamous Cell Carcinoma: Correlation with Tumor Progression and Poor Prognosis

Objective: To identify genes associated with therapeutic targets of oral squamous cell carcinoma (OSCC), we compared gene expression profiles in OSCC-derived cell lines with human normal oral keratinocytes. Methods: We analyzed the gene expression profiles of OSCCs using Affymetrix GeneChip analysis. The identified genes were analyzed by an Ingenuity Pathway Analysis tool to identify networks of interacting genes. A candidate gene was further evaluated for the expression status of the mRNA and protein in OSCC-derived cell lines and primary OSCCs. Results: The microarray data identified 188 genes downregulated in OSCC-derived cell lines, and the genetic pathways associated with expression changes were generated. Among the genes mapped to the network with the highest significance, carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) was analyzed further. CEACAM1 mRNA and protein were frequently downregulated in OSCC-derived cell lines compared with human normal oral keratinocytes. Immunohistochemical analysis showed that primary OSCCs were significantly decreased in CEACAM1. Moreover, CEACAM1 expression was correlated with the TNM staging. We also found that CEACAM1-negative expression was significant both for disease-free (p = 0.036) and overall survival (p = 0.032). Conclusion: Repression of CEACAM1 could contribute to cancer progression and may indicate a poor prognosis for patients with OSCC.

Upregulated expression of ADAM12 is associated with progression of oral squamous cell carcinoma

ADAMs are a disintegrin and metalloproteinase family of membrane-associated metalloproteinases characterized by their multidomain structure, and have been reported to be associated with various malignant tumors. The aim of this study was to identify crucial members of the ADAM family in oral squamous cell carcinoma (OSCC), and to reveal their biological function and clinical significance. To clarify whether ADAM family genes are involved in OSCC, changes in the expression profile were investigated by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis and immunohistochemical analysis. Functional analysis was performed by comparing cellular proliferation of siADAM-transfected cell lines and parental cell lines. Real-time qRT-PCR analysis identified significantly upregulated expression of ADAM12 in OSCC-derived cell lines. This was validated in OSCC samples using real-time qRT-PCR and immuno-histochemical staining. ADAM12 expression was correlated with TNM classification; significantly greater expression of ADAM12 was observed in tumors with higher T classification and more advanced stages. Moreover, siADAM12-transfected cells showed both a suppressed proliferation rate and increased transforming growth factor (TGF)-β3 expression. Our data indicate that ADAM12 is overexpressed in OSCC and might accelerate cellular proliferation. Its function may be associated with TGF-β signaling. This study suggests that controlling the expression or activity of ADAM12 could be a useful strategy in the development of an effective cure for OSCC.

Human Immunodeficiency Virus–Associated Burkitt's Lymphoma in Oral Cavity of Japanese Patient

olescents and is associated with EBV infection in 95% of cases. The jawbone is the most commonly affected region. The human immunodeficiency virus (HIV)related form develops in adults and is associated with positive titers of EBV in about 30% of cases. Abdominal extranodal lesions and lymph node involvement are common in this form of BL. 2,3 The oral manifestation of BL in HIV-infected individuals is, however, uncommon in the English-language medical literature, and its treatment and clinical course have not been fully documented. The present case report describes a patient with HIV-associated BL in the mandibular gingiva. This patient was successfully treated with intensive chemotherapy combined with highly active antiretroviral therapy (HAART). The characteristics of HIV-related oral BL are also discussed in the context of published reports. We report a case of BL arising in the oral cavity of a 45-year-old Japanese woman with HIV infection.

Antitumor activity of satraplatin in cisplatin-resistant oral squamous cell carcinoma cells

The aim of the current study was to identify the antitumor activity of satraplatin in paired cisplatin (CDDP)‐resistant oral squamous cell carcinoma (OSCC) cell line and its parental cell line.