Natsumi Takamaru

Effects of low crystalline carbonate apatite on proliferation and osteoblastic differentiation of human bone marrow cells

Carbonated apatite (CO3Ap) is the inorganic component of bone. We have proposed a new method for the fabrication of CO3Ap blocks based on a dissolution-precipitation method using a synthetic precursor. The aim of this study is to examine the effects of low crystalline CO3Ap on initial cell attachment, proliferation and osteoblastic differentiation of human bone marrow cells (hBMCs) using sintered hydroxyapatite and tissue culture plates as controls. Initial cell attachment and proliferation were assessed with a MTT assay. Expression of osteoblastic markers was examined by reverse transcription-polymerase chain reaction. XRD and FT-IR results showed formation of B-type carbonate apatite with lower crystallinity. No difference was observed for initial cell attachment between HAp and CO3Ap discs. hBMSC attached more significantly on tissue culture plate than on HAp and CO3Ap discs. The number of cells on HAp was higher than that on CO3Ap until day 7, after which the number of cells was similar. hBMSC proliferated more significantly on tissue culture plate than on HAp and CO3Ap discs. In contrast, hBMCs incubated on CO3Ap demonstrated much higher expression of osteoblastic markers of differentiation, such as type I collagen, alkaline phosphatase, osteopontin and osteocalcin, than hBMCs on HAp. On the tissue culture plate, they were not any change throughout the culture period. These results demonstrated that low crystalline CO3Ap exhibit higher osteoinductivity than HAp.

Bortezomib-enhanced radiosensitization through the suppression of radiation-induced nuclear factor‑κB activity in human oral cancer cells

Oral cancer cells have a significantly augmented nuclear factor-κB (NF-κB) activity and the inhibition of this activity suppresses tumor growth. Bortezomib is a proteasome inhibitor and a drug used for molecular-targeted therapy (targets NF-κB). In this study, we investigated whether bortezomib would be effective as an inhibitor of proliferation and a radiosensitizer for the treatment of oral cancer. We demonstrate that bortezomib inhibits NF-κB activity and cell proliferation. The combined treatment with bortezomib and radiation (RT) suppressed NF-κB activity and cell growth in vitro and in vivo compared with RT treatment alone. To investigate the mechanisms by which bortezomib suppresses tumor growth, the expression of signaling molecules downstream of NF-κB were examined by ELISA. The combined treatment significantly inhibited the radiation-induced production of angiogenic factors and decreased the number of blood vessels in the tumor tissues. Although the expression of anti-apoptotic proteins was upregulated by RT, bortezomib downregulated the RT-induced expression of these proteins. Moreover, the expression of cleaved poly(ADP-ribose) polymerase in vitro and in vivo was enhanced by bortezomib, indicating that bortezomib inhibits tumor growth by inducing apoptosis. This study clearly demonstrates that bortezomib significantly inhibits tumor growth and that the combined treatment with bortezomib and RT results in a significant inhibition of tumor growth. The mechanisms underlying the inhibition of tumor growth by bortezomib include the suppression of angiogenesis and the induction of apoptosis. A novel molecular targeting therapy including bortezomib may be effective in the treatment of oral cancer by suppressing NF-κB activity.

Antitumor efficacy of sequential treatment with docetaxel and 5-fluorouracil against human oral cancer cells.

Docetaxel (DOC) and 5-fluorouracil (5-FU) are important anticancer agents widely used in the treatment of a variety of cancers including oral squamous cell carcinoma (OSCC). The purpose of this study was to determine the antitumor efficacy of the sequential administration of DOC and 5-FU against OSCC cells (B88 and CAL27 cells) in vitro and in vivo. In in vitro growth inhibition assays, sequential treatment with DOC followed by 5-FU was more effective in inhibiting cancer cell growth than 5-FU followed by DOC, single treatment with DOC or 5-FU, or combined treatment with DOC and 5-FU. Furthermore, DOC followed by 5-FU significantly inhibited tumor growth in vivo compared to 5-FU followed by DOC. To understand the mechanisms underlying the enhanced growth inhibitory effect of the administration sequence, DOC followed by 5-FU, we examined the expression of 5-FU metabolic enzymes such as thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyl transferase (OPRT), which were known to regulate the antitumor effect of 5-FU, by real-time RT-PCR and western blot analysis. Downregulation of TS and DPD expression and upregulation of OPRT expression were induced by DOC treatment, suggesting that DOC enhanced the efficacy of 5-FU by altering the expression of its metabolic enzymes. These results indicate that sequential treatment with DOC followed by 5-FU could be a promising therapeutic strategy for oral cancer.

The role of metabotropic glutamate receptor 5 on the stromal cell-derived factor-1/CXCR4 system in oral cancer.

We have demonstrated that blocking CXCR4 may be a potent anti-metastatic therapy for CXCR4-related oral cancer. However, as CXCR4 antagonists are currently in clinical use to induce the mobilization of hematopoietic stem cells, continuous administration as an inhibitor for the metastasis may lead to persistent leukocytosis. In this study, we investigated the novel therapeutic downstream target(s) of the SDF-1/CXCR4 system, using B88-SDF-1 cells, which have an autocrine SDF-1/CXCR4 system and exhibit distant metastatic potential in vivo. Microarray analysis revealed that 418 genes were upregulated in B88-SDF-1 cells. We identified a gene that is highly upregulated in B88-SDF-1 cells, metabotropic glutamate receptor 5 (mGluR5), which was downregulated following treatment with 1,1’ -[1,4-Phenylenebis(methylene)]bis-1,4,8,11-tetraazacyclotetradecane octahydrochloride (AMD3100), a CXCR4 antagonist. The upregulation of mGluR5 mRNA in the SDF-1/CXCR4 system was predominately regulated by the Ras-extracellular signal-regulated kinase (ERK)1/2 pathway. Additionally, the growth of B88-SDF-1 cells was not affected by the mGluR5 agonist (S)-3,5-DHPG (DHPG) or the mGluR5 antagonists 2-Methyl-6-(phenylethynyl)pyridine (MPEP) and 3-((2-Methyl-1,3-thiazol-4-yl)ethynyl)pyridine (MTEP). However, we observed that DHPG promoted B88-SDF-1 cell migration, whereas both MPEP and MTEP inhibited B88-SDF-1 cell migration. To assess drug toxicity, the antagonists were intraperitoneally injected into immunocompetent mice for 4 weeks. Mice injected with MPEP (5 mg/kg) and MTEP (5 mg/kg) did not exhibit any side effects, such as hematotoxicity, allergic reactions or weight loss. The administration of antagonists significantly inhibited the metastasis of B88-SDF-1 cells to the lungs of nude mice. These results suggest that blocking mGluR5 with antagonists such as MPEP and MTEP could prevent metastasis in CXCR4-related oral cancer without causing side effects.

Fabrication and Physical Evaluation of Gelatin-Coated Carbonate Apatite Foam

Carbonate apatite (CO3Ap) foam has gained much attention in recent years because of its ability to rapidly replace bone. However, its mechanical strength is extremely low for clinical use. In this study, to understand the potential of gelatin-reinforced CO3Ap foam for bone replacement, CO3Ap foam was reinforced with gelatin and the resulting physical characteristics were evaluated. The mechanical strength increased significantly with the gelatin reinforcement. The compressive strength of gelatin-free CO3Ap foam was 74 kPa whereas that of the gelatin-reinforced CO3Ap foam, fabricated using 30 mass % gelatin solution, was approximately 3 MPa. Heat treatment for crosslinking gelatin had little effect on the mechanical strength of the foam. The gelatin-reinforced foam did not maintain its shape when immersed in a saline solution as this promoted swelling of the gelatin; however, in the same conditions, the heat-treated gelatin-reinforced foam proved to be stable. It is concluded, therefore, that heat treatment is the key to the fabrication of stable gelatin-reinforced CO3Ap foam.

Antitumour effect of valproic acid against salivary gland cancer in vitro and in vivo

Salivary gland cancer (SGC) has a comparatively poor prognosis and is prone to frequent recurrence and metastases. Therefore, the development of more effective chemotherapy against SGC is desirable. The aim of the present study was to investigate the antitumour effects of valproic acid (VPA) against SGC in vitro and in vivo. Two human SGC cell lines (HSY and HSG cells) were used in the present study. The effects of VPA on the proliferation of SGC cells in vitro were assessed by MTT assay. Cancer cells treated with VPA were subjected to cell cycle analysis by flow cytometry. In addition, the expression levels of p21 and p27 were examined by real-time RT-PCR to identify the mechanisms of the antitumour effect of VPA on SGC. The effects of VPA on cancer growth in vivo were evaluated in a xenograft model. VPA inhibited the proliferation of SGC cells in a dose-dependent manner in vitro. Degenerated cancer cells were observed at high concentrations of VPA. In the cell cycle analysis, VPA induced cell-growth inhibition and G1 arrest of cell cycle progression in both cancer cell lines in a time- and dose-dependent manner. VPA markedly upregulated the mRNA expression levels of both p21 and p27 in both SGC cell lines in a time-dependent manner. In the xenograft model experiment, VPA treatment markedly inhibited the growth of salivary gland tumours when compared with the growth of the untreated controls. VPA may be a valuable drug in the development of better therapeutic regimens for SGC.

Abstract 4954: The expression of X-linked inhibitor of apoptosis in human oral squamous cell carcinoma and its relationship with clinical factors

[Background] X-linked inhibitor of apoptosis (XIAP) is a member of the inhibitor of apoptosis protein family, which is associated with cell survival by blocking caspase-mediated apoptosis. XIAP is expressed in various malignant tumors. The overexpression of XIAP has been reported to be a poorer prognostic factor in various malignancies. However, the prognostic value of XIAP expression in patients with oral cancer is not still cleared. [Purpose] The aims of present study were to evaluate the expression of XIAP protein in oral squamous cell carcinoma (OSCC) and to elucidate the relationships among the XIAP expression, clinical stages, histological differentiation and classification of invasion mode. [Materials and Methods] Four human OSCC cell lines, B88, CAL27, HNt, and HSC3 cells were used in this study. Normal gingival epithelial cells served as control. XIAP expression of cultured cells was detected by western blot. Tissue specimens were obtains from 85 patients with OSCC after surgery or biopsy. XIAP expression was detected by an immunohistochemical method. [Results] The expression of XIAP was detected in all cancer cells, but not in normal cells. Immunohistochemical analysis of 85 cases of OSCC showed that 73 (86%) cases expressed XIAP. There was no relationship between XIAP expression and clinical stages, or classification of invasion mode. There were significant differences between XIAP expression and histological differentiation. Most of non-staining and weakly staining of cancer was well differentiated. In contrast, intense and extensive staining was frequently found in poorly differentiated cancer. [Conclusions] These findings suggested that the expression of XIAP in OSCC could be related to histological differentiation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4954. doi:1538-7445.AM2012-4954

Expression of CD44, CD44v9, ABCG2, CD24, Bmi‑1 and ALDH1 in stage I and II oral squamous cell carcinoma and their association with clinicopathological factors

Cancer stem cells (CSCs) exhibit self-replication, self-differentiation, drug resistance and immune evasion activities. In recent years CSCs have become increasingly important for the treatment of malignant tumors. CSCs express specific markers, including cluster of differentiation (CD)44, CD44 variant 9 (CD44v9), ATP-binding cassette sub-family G member 2 (ABCG2), CD24, B lymphoma Mo-MLV insertion region 1 homolog (BMI-1) and aldehyde dehydrogenase 1 (ALDH1). However, the prognostic value of their expression in patients with oral squamous cell carcinoma (OSCC) are not well known. The present study evaluated these markers in stage I and II patients with OSCC and examined the association between T classification, histological differentiation, classification of invasion mode, lymph node metastasis and disease-free survival rate. Tissue specimens were obtained from 70 patients with stage I or II OSCC following either surgery or biopsy. Immunohistochemistry was performed and positive staining was defiend as 10% positive cells. CD44 and CD44v9 expressions were strongly detected in all OSCC tissues compared with normal epithelial cells. A total of 22 (31.4%) cases expressed ABCG2 and there was a significant association between ABCG2 expression and invasion. A total of 41 cases (59.0%) expressed CD24 and there was a significant association between CD24 expression and invasion. A total of 33 cases (47.1%) expressed BMI-1 and there was a significant association between BMI-1 expression and the disease-free survival rate. A total of 18 cases (25.7%) expressed ALDH1. Although there was no association between ALDH1 expression and T classification, there were significant associations between ALDH1 expression and histological differentiation, invasion mode, metastasis and the disease-free survival rate. Multivariate analysis revealed that ALDH1 expression was the only prognostic factor for disease-free survival rate. The results of the present study suggest that the positivity of ALDH1 detected in patients with OSCC correlates with the number of cells undergoing epithelial mesenchymal transition and metastasis. These findings indicated that the expression of ALDH1 may be an effective prognostic marker indicating the survival of patients with stage I and II OSCC.

Abstract 3879: Expression of sox2 and oct4 in human oral squamous cell carcinoma and its relationship with clinical factors

Background: A cancer stem cell (cancer initiating cell, CSC) is considered capable of self -replication, self-differentiation, drug resistance, and immune evasion. Recently, CSC has become increasingly important in the treatment of malignant tumors. Cancer stem cells express specific molecules termed CSC marker, including sex determining region Y-box2 (SOX2), and octamer-binding transcription factor 4 (Oct4), and their expression has been reported to be the potential prognostic values. However, the prognostic values of SOX2 and Oct4 expression in patients with oral cancer are less understood. [Purpose]The aims of present study were to evaluate the expression of SOX2 and Oct4 in oral squamous cell carcinoma (OSCC) and to elucidate the relationships among the CSC marker expression, clinical stages, histological differentiation, the classification of invasion mode, cerebral lymph node metastasis, distant metastasis, and disease-free survival rate. Materials and Methods: Tissue specimens were obtains from 108 patients with OSCC after surgery or biopsy. Immunohistochemistry was used to assess SOX2 and Oct4 protein using at least 10% staining-positive cells as the definition of positive staining. Results: Immunohistochemical analysis of 108 cases showed that 42 cases (39%) expressed SOX2. There was no significant association between SOX2 expression and tumor size, invasion mode or histological differentiation. However, there was significant association between SOX2 expression and distant metastasis or disease-free survival rate at stage 1 and 2 patients (73 cases). Otherwise, seventy cases (65%) cases of 108 OSCC patients expressed Oct4. There was significant association between Oct4 expression and histological differentiation. There was no significant association between Oct4 expression and tumor size, invasion mode, metastasis, or disease-free survival rate. Conclusions: These findings suggested that the expression of SOX2 may be good marker indicating survival in patients with OSCC. Citation Format: Tetsuya Tamatani, Natsumi Takamaru, Go Ohe, Keiko Kudo, Takaharu Kudo, Akira Takahashi, Yoshiko Yamamura, Kenji Fujisawa, Hirokazu Nagai, Youji Miyamoto. Expression of sox2 and oct4 in human oral squamous cell carcinoma and its relationship with clinical factors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3879. doi:10.1158/1538-7445.AM2017-3879

Abstract 3358: Expression of ALDH1, Bmi-1 and CD24 in human oral squamous cell carcinoma and its relationship with clinical factors

[Background] A cancer stem cell (cancer initiating cell, CSC) is considered capable of self -replication, self-differentiation, drug resistance, and immune evasion. Recently, CSC has become increasingly important in the treatment of malignant tumors. Cancer stem cells express specific molecules termed CSC marker, including aldehyde dehydrogenase (ALDH) 1, B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) and CD24, and their expression has been reported to be the potential prognostic values. However, the prognostic values of ALDH1, Bmi1, and CD24 expression in patients with oral cancer are less understood. [Purpose] The aims of present study were to evaluate the expression of ALDH1, Bmi1, and CD24 in oral squamous cell carcinoma (OSCC) and to elucidate the relationships among the CSC marker expression, clinical stages, histological differentiation, the classification of invasion mode, cerebral lymph node metastasis and disease-free survival rate. [Materials and Methods] Tissue specimens were obtains from 103 patients with OSCC after surgery or biopsy. Immunohistochemistry was used to assess ALDH1, Bmi1, and CD24 protein using at least 10% staining-positive cells as the definition of positive staining. [Results] Immunohistochemical analysis of 103 cases showed that 31 cases (30%) expressed ALDH1. There was no relationship between ALDH1 expression and clinical stages or metastasis. However, there was significant association between ALDH1 expression and histological differentiation, or classification of invasion mode or disease-free survival rate. Otherwise, 39 cases (38%) cases of 103 OSCC patients expressed Bmi-1. There was significant association between Bmi-1 expression and invasion mode or disease-free survival rate. Sixty four cases (62%) expressed CD24. There was significant association between CD24 expression and histological differentiation. [Conclusions] These findings suggested that the expression of ALDH1 and Bmi-1 as CSC markers in OSCC may be good marker indicating survival in patients with OSCC. Citation Format: Tetsuya Tamatani, Natsumi Takamaru, Kenji Fujisawa, Hirokazu Nagai, Youji Miyamoto. Expression of ALDH1, Bmi-1 and CD24 in human oral squamous cell carcinoma and its relationship with clinical factors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3358.