Biomedical subjects

Satoru Shintani

Publications and source records attributed to Satoru Shintani.

36 records · Page 2Linked to original sources

PubMed2003

Enhancement of tumor radioresponse by combined treatment with gefitinib (Iressa, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, is accompanied by inhibition of DNA damage repair and cell growth in oral cancer.

Molecular blockade of EGFR with either an EGFR MAb or an EGFR TKI enhances the radiosensitivity of human SCCs. In the present study, we investigated whether treatment with the EGFR TKI gefitinib (Iressa, ZD1839) improves the response to radiotherapy in the OSCC cell lines HSC2 and HSC3. We examined potential mechanisms that may contribute to the enhanced radiation response induced by gefitinib. Growth inhibition was observed in vitro with radiation or gefitinib. A cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. Cells treated with a combination of radiation and gefitinib arrested in G(1) and G(2)-M phases, with a decrease in the S-phase population. While radiation alone did not significantly affect MEK1/2 and p38 MAPK autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Results from DNA damage repair analysis in cultured OSCC cells demonstrated that gefitinib had a strong inhibitory effect on DNA-PKc pathways after radiation. Tumor xenograft studies demonstrated that the combination of gefitinib and radiation caused growth inhibition and tumor regression of well-established OSCC tumors in athymic mice; tumor volume was reduced from 1,008.2 to 231.4 mm(3) in HSC2 cells (p < 0.01) and from 284.2 to 12.4 mm(3) in HSC3 cells (p < 0.01). Immunohistochemical analysis of OSCC xenografts revealed that gefitinib caused a striking decrease in tumor cell proliferation when combined with radiotherapy. Overall, we conclude that gefitinib enhances tumor radioresponse by multiple mechanisms that may involve antiproliferative growth inhibition and effects on DNA repair after exposure to radiation.

Animals↗

PubMed2003

Gefitinib ('Iressa'), an epidermal growth factor receptor tyrosine kinase inhibitor, mediates the inhibition of lymph node metastasis in oral cancer cells.

High expression of epidermal growth factor receptor (EGFR) is frequently observed in many solid tumor types including oral squamous cell carcinomas (OSCC). This study investigated whether treatment with gefitinib ('Iressa'), an EGFR-tyrosine kinase inhibitor, would inhibit the metastatic spread in OSCC cells. This was evaluated using orthotopic xenografts of highly metastatic OSCC. Metastasis was observed in six of 13 gefitinib treated animals (46.2%), compared with all of 12 control animals (100%). After exposure to gefitinib, OSCC cells showed a marked reduction in cell adhesion ability to fibronectin and in the expression of integrin alpha3, alphav, beta1, beta4, beta5 and beta6.

Animals↗

PubMed2003

Flavopiridol, a cyclin dependent kinase (CDK) inhibitor, induces apoptosis by regulating Bcl-x in oral cancer cells.

Flavopiridol is a synthetic flavone that inhibits tumor growth by suppressing cyclin-dependent kinases (CDKs). We have investigated effects of flavopiridol in oral squamous cell carcinoma (OSCC). Flavopiridol was found to inhibit the growth of OSCC cells in a time- and dose-dependent manner. Induction of apoptosis was observed in all cells showing accumulated cells with sub-G(1) DNA contents, DNA fragmentations, and PARP cleavages. While Bcl-2 and Bax expression did not change, Bcl-x(L) was down regulated and Bcl-xs was up-regulated after being exposed to flavopiridol. Flavopiridol treatments also resulted in remarkable reductions of cyclin A, cyclin B, and cyclin D1 expressions. We also found that expression levels of CDK activation kinase and CDC25C were reduced, and p34 inactive form CDK2 were up-regulated. Our data indicate that flavopiridol has growth inhibition activities against OSCC. Flavopiridol not only inhibits CDKs directly, but it also inhibits the CDKs activation pathway and activates the Bcl-x apoptotic pathway.

Antineoplastic Agents↗

PubMed2003

Thiazolidinediones inhibit cell growth of human oral squamous cell carcinoma in vitro independent of peroxisome proliferator-activated receptor gamma.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. Recently, we have demonstrated that PPARgamma is expressed in human salivary gland tumors and its ligands inhibit the growth of cultured salivary gland cancer cells. However, expression and function of PPARgamma in normal and neoplastic human oral squamous epithelium remains unclear. In the present study, we examined PPARgamma expression in human oral squamous cell carcinoma (OSCC) and tested its ligands for any antitumor effect. PPARgamma mRNA was detected by RT-PCR in some OSCC tissues and cultured cells, but the PPARgamma protein showed neither expression nor ligand-induced transcriptional activity. Despite loss of PPARgamma function, synthetic PPARgamma ligands caused significant dose-dependent inhibition of cancer cell growth. These results suggest that PPARgamma function is inactivated in OSCC cells and the anti-proliferative effect of its synthetic ligands is independent of PPARgamma.

Carcinoma, Squamous Cell↗

PubMed2003

Enhancement of radiosensitivity in head and neck cancer cells by ZD1839 ('IRESSA'), a selective epidermal growth factor receptor tyrosine kinase inhibitor.

Overexpression of epidermal growth factor receptor (EGFR) is frequently observed in many solid tumor types, including head and neck squamous cell carcinomas (HNSCC). Recent laboratory experiments have demonstrated that high EGFR levels correlate with increased tumor resistance to radiation. This study investigated the relationship between EGFR expression levels and radiosensitivity in 5 HNSCC cell lines (HSC2, HSC3, HSC4, SCC25, and Ca9-22) and whether treatment with ZD1839 ('Iressa'), a selective EGFR-tyrosine kinase inhibitor (TKI), would improve tumor cell response to radiotherapy. ZD1839 suppressed the growth of HNSCC cell lines in a dose- and time-dependent manner. Radiosensitivity of these HNSCC cell lines, assessed by a clonogenic survival assay, differed greatly and the expression of EGFR varied. EGFR expression levels (EGFR numbers/cell) correlated with increased tumor resistance to radiation (f[x]= 4.54 X, R2 = 0.715; f[x]: EGFR numbers/cell, X: radiosensitivity; D10). Following exposure of the HNSCC cells to 1.0 microM ZD1839 and radiation (0-10 Gy), greater than additive growth inhibitory effects were observed. These results suggest that ZD1839 could enhance tumor radiosensitivity and inhibit tumor growth after radiation, indicating that this combination could have clinical potential in the treatment of patients with head and neck cancer.

Antineoplastic Agents↗

PubMed2003

Up-regulation of DNA-dependent protein kinase correlates with radiation resistance in oral squamous cell carcinoma.

DNA-PK is a nuclear protein with serine/threonine kinase activity and forms a complex consisting of the DNA-PKcs and a heterodimer of Ku70 and Ku80 proteins. Recent laboratory experiments have demonstrated that the DNA-PK complex formation is one of the major pathways by which mammalian cells respond to DNA double-strand breaks induced by ionizing radiation. In this study, we evaluated the relationship between expression levels of DNA-PKcs, Ku70 and Ku80 proteins and radiation sensitivity in oral squamous cell carcinoma (OSCC) cell lines and in OSCC patients treated with preoperative radiation therapy. The OSCC cell lines greatly differed in their response to irradiation, as assessed by a standard colony formation assay. However, the expression levels of the DNA-PK complex proteins were all similar, and there was no association between the magnitude of their expression and the tumor radiation sensitivity. Expression of DNA-PK complex proteins increased after radiation treatment, and the increased values correlated with the tumor radiation resistance. Expression of DNA-PKcs and Ku70 after irradiation was increased in the surviving cells of OSCC tissues irradiated preoperatively. These results suggest that up-regulation of DNA-PK complex protein, especially DNA-PKcs, after radiation treatment correlates to radiation resistance. DNA-PKcs might be a molecular target for a novel radiation sensitization therapy of OSCC.

Adult↗

PubMed2003

Skp2 and Jab1 expression are associated with inverse expression of p27(KIP1) and poor prognosis in oral squamous cell carcinomas.

Previous studies have shown that low levels of p27(KIP1), an inhibitor of G1 cyclin-dependent kinases (CDK), are associated with high aggressiveness and poor prognosis in a variety of cancers. Decreased levels of p27(KIP1) are caused, at least in part, by an acceleration of degradation with Skp2 (S-phase kinase-associated protein 2) and Jab1 (Jun activation domain-binding protein 1). This investigation was undertaken to examine whether the Skp2 and Jab1 expression is correlated with p27(KIP1) protein levels, and how it is clinically relevant in oral squamous cell carcinoma (OSCC). The correlations between p27(KIP1) and Skp2, and p27(KIP1) and Jab1 expression were evaluated by Western blot analysis. Immunohistochemical analysis was done in 75 cases of OSCC. A strongly significant inverse correlation was found between levels of p27(KIP1) and Skp2, and p27(KIP1) and Jab1 (p < 0.0001). Thus, decreased levels of p27(KIP1) were associated with strongly increased levels of Skp2 and Jab1, whereas high levels of p27(KIP1) coincided with low levels of Skp2 and Jab1. Reductions of p27(KIP1) expression and overexpression of Skp2 and Jab1 were significantly associated with cervical lymph node metastasis and poor prognosis. Overexpression of Skp2 and Jab1 is associated with the reduction of p27(KIP1) expression, and may have a role in the progression of OSCC.

Biomarkers, Tumor↗

PubMed2003

Detection of circulating cancer cells in human oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) cells can invade adjacent tissues and the vascular system at an early stage of tumor progression. In the present study, we have attempted to detect circulating cancer cells. We used human OSCC cells expressing green fluorescent protein (GFP) in an orthotopic nude mouse model and were able to detect GFP-expressing cells using a fluorescence activated cell sorter and fluorescence microscopy. We also detected the expression of GFP, squamous cell carcinoma antigen (SCCA), or epidermal growth factor receptor (EGFR) mRNA in the blood of tumor-bearing mice by conventional reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time quantitative RT-PCR (TaqMan RT-PCR). TaqMan RT-PCR was the more sensitive method to detect the circulating cancer cells. Furthermore, we examined the expression of SCCA and EGFR mRNA in the peripheral blood of patients with OSCC by conventional RT-PCR and TaqMan RT-PCR. We detected SCCA and EGFR mRNA in few cases by conventional RT-PCR, whereas TaqMan RT-PCR showed their expression in about 50% of cases. However, there was no correlation between detection of circulating viable cancer cells and metastasis to lymph nodes and distant organs. These results suggest that TaqMan RT-PCR is a very useful method and both SCCA and EGFR mRNA may be available as a marker for detection of circulating cancer cells.

Animals↗

PubMed2003

[A case of mandibular gingival cancer (T4) responding to concurrent chemoradiotherapy with TS-1].

We report here a patient with advanced oral cancer in which concurrent chemoradiotherapy with TS-1 was performed. The patient was an 82-year-old male who had a 41 x 22 mm tumor mass around the left lower gingiva, whose X-ray showed a bone resorption image reaching the mandibular canal. We carried out concurrent chemoradiotherapy with TS-1. After 4 weeks, severe side effects, i.e., stomatitis and diarrhea, force us to discontinue the treatment. However, the tumor had begun to shrink from the 2nd week of treatment, and had clinically disappeared by the 8th week. The histopathological examination also indicated a complete response (CR). Thus, this treatment was very effective and may be useful for advanced cases.

Aged↗

PubMed2003

[A clinical study of neoadjuvant radiochemotherapy with docetaxel and cisplatin for oral cancers].

Docetaxel is classified among the microtubule-inhibiting compounds called taxanes, which are currently used as agents to treat head and neck cancers. To investigate the efficacy and safety of a neoadjuvant radiation therapy combined with docetaxel/cisplatin, we used this combination to treat 6 patients with oral squamous cell carcinoma. The patients received a low-dose fraction of docetaxel (20 mg/m2/week; total dose: 123.0 +/- 35.0 mg) and cisplatin (5 mg/m2/day, 5 days a week; total dose: 160.0 +/- 42.1 mg) combined with simultaneous irradiation of 40 Gy. Of the 6 patients, 5 (83.3%) showed a partial response (PR) and 1 showed no response (NC). Pathological efficacy was revealed in 4 patients (66.7%). All patients experienced stomatitis over grade 2, and 4 experienced neutropenia.

Adult↗

PubMed2002

Expression of cell cycle control proteins in normal epithelium, premalignant and malignant lesions of oral cavity.

In this study, we examined the expression of cyclins, cyclin dependent kinase (CDKs) and CDK inhibitors by immunohistochemical analysis in 20 normal mucosa, 42 epithelial dysplasia (ED), and 117 oral squamous cell carcinoma. Neither Cyclin D1 nor CDK2 were detectable in normal tissue and ED. Their presence, however, was detectable in squamous cell carcinoma (SCCs) (Cyclin D1, 35.9%; CDK2, 66.7%). Cyclin E was detectable in 57.1% of severe ED and 62.8% of SCCs. For the CDK inhibitors, these proteins were detectable in all normal mucosa and most of the mild and moderate ED. For severe ED, expression of these proteins was not observed in some cases (p12(DOC-1), 14.3%; p16(INK4A), 28.6%; p27(KIP1), 7.1%). For SCCs, the expression of p12(DOC-1) was lost in 71.8%, p16(INK4A) in 69.2% and p27(KIP1) in 35.9%. These results suggest that elevated expression of cyclin D1, cyclin E, CDK2 and loss of p12(DOC-1), p16(INK4A) and p27(KIP1) may contribute to the multistep nature of oral carcinogenesis.

Biomarkers, Tumor↗

PubMed2002

Lymph node metastasis of oral cancer visualized in live tissue by green fluorescent protein expression.

Here, we report the establishment of a stably transfected cell line which expresses high levels of green fluorescent protein (GFP), thus permitting the detection and visualization of developing tumors and lymph node metastases after injection into nude mice. Cells of the human oral squamous carcinoma cell line (SAS-L1) were transfected with an expression vector containing a cDNA encoding humanized GFP and the neomycin resistance gene. A clone with stable high-level expression of GFP was selected in vitro using G418. To study metastasis formation, GFP-expressing cells were injected orthotopically into the tongue of nude mice. The resultant tumor growth in the tongue and micrometastases in the lymph nodes could be visualized by GFP fluorescence. Therefore a useful model has been developed for the study of oral cancer, firstly to understand the metastatic process and secondly for the evaluation of potential treatments.

Animals↗

PubMed2002

Anti-epidermal growth factor receptor monoclonal antibody 225 upregulates p27(KIP1) and p15(INK4B) and induces G1 arrest in oral squamous carcinoma cell lines.

Epidermal growth factor receptor (EGFR) regulates the growth and progression of human oral squamous cell carcinoma (SCC). Recently, the link between EGFR signaling and the cell cycle has been identified. Some reports have described that EGFR-blocking monoclonal antibody 225 (mAb225) induced G1 arrest and inhibited the growth of various cancer cells. The purpose of this study was to evaluate the effect of mAb225 on human oral SCC cell lines. Exposure to mAb225 in culture inhibited the growth of oral SCC cell lines in an EGFR number-independent manner, with the percent inhibition ranging from 13.8 to 76.6%. Flow-cytometric analysis demonstrated that treatment with mAb225 induced cell accumulation in G1 phase, accompanied by a decrease in the percentage of cells in the S phase. Apoptosis was not seen in this study. G1 arrest was accompanied by a decrease in CDK2-, CDK4-, and CDK6-associated histone H1 kinase activities, and an increase in the expression levels of cell cycle inhibitors p27(KIP1) and p15(INK4B). These results suggested that the antiproliferative effect of EGFR blockade by mAb225 in oral SCC may be mediated by p27(KIP1) and p15(INK4B).

Antibodies, Monoclonal↗

PubMed2002

Expression of peroxisome proliferator-activated receptor gamma and the growth inhibitory effect of its synthetic ligands in human salivary gland cancer cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. It is expressed in several tissue types, including adipose tissue in which it stimulates adipogenesis. Recent studies have demonstrated that PPARgamma ligands induce cellular differentiation and inhibit cell growth in carcinomas of various organs including the breast, prostate, lung, colon, stomach, bladder, and pancreas. However, whether PPARgamma is expressed in human salivary gland tumors and its function in this tissue is unknown. In the present study, we examined PPARgamma gene expression in human salivary gland cancer cells and tested its ligands for any antitumor effect. PPARgamma mRNA was detected by RT-PCR in both benign and malignant salivary gland tumor tissues. The effect of PPARgamma on cell growth was investigated using four human salivary gland cancer cell lines; HSG, AZA3, HSY and TYS, which were confirmed to express PPARgamma1 mRNA and protein. Retinoid X receptor alpha protein, which forms heterodimers with PPARgamma, was also detected in all the cells tested. Data obtained by luciferase assay indicated that the intrinsic PPARgamma protein was activated by the synthetic ligands, troglitazone and pioglitazone, but not by the natural ligand, 15-deoxy-delta12, 14-prostaglandin J2. The synthetic PPARgamma ligands, particularly troglitazone, caused significant dose-dependent inhibition of cancer cell growth. Furthermore, the overexpression of PPARgamma1 or PPARgamma2 in cancer cells also reduced significantly their growth rate. These results suggest that PPARgamma and its synthetic ligands suppress the growth of human salivary gland cancer cells and it may be a useful molecular target for cancer treatment.

Blotting, Western↗

PubMed2002

Cyclin-dependent kinase inhibitor (roscovitine) suppresses growth and induces apoptosis by regulating Bcl-x in head and neck squamous cell carcinoma cells.

Cyclin-dependent kinases (Cdks) play essential roles in the intracellular controls of the cell cycles. Roscovitine, [2-(R)-(1-ethyl-2-hydroxyethylamino)-6-benzylamino-9-isopropylpurine], is a potent and selective inhibitor of the Cdk2 and Cdc2. We investigated whether this compound was effective against head and neck squamous cell carcinoma (HNSCC) cells. Roscovitine was found to inhibit the growth of all 11 HNSCC cell lines in time- and dose-dependent manner and to diminish the Cdk2 and Cdc2 activities. An induction of apoptosis was observed in all cells, as judged by the cell morphology, along with the appearance of cells with sub-G1 DNA contents, DNA fragmentations, and poly(ADP-ribose) polymerase (PARP) cleavage. In four HNSCC cell lines, apoptosis was induced without antecedent marked cell cycle arrest, and in the other seven cell lines, cell cycle arrest preceded cell death. We also found up-regulation of Bcl-xS in the former cell lines, and in the latter cell lines, the expressions of Bcl-2 and Bcl-xL were induced simultaneously. These results suggest that roscovitine exerts antitumor activities in HNSCC and is associated with induction of Bcl-xS. Roscovitine can be considered to provide a new chemopreventive and chemotherapeutic strategy for the clinical management of HNSCC.

Apoptosis↗

PubMed2002

[Non-randomized clinical study comparing chemotherapy plus radiotherapy with radiotherapy alone in neoadjuvant therapy for oral cancer].

Neoadjuvant therapy plays an important role for organ preservation and survival rate in the treatment of oral cancer. We clinically compared the effect of neoadjuvant radiotherapy and chemoradiotherapy in patients with oral cancer. We retrospectively examined 47 patients diagnosed with oral squamous cell carcinoma who underwent neoadjuvant therapy followed by curative surgery in the oral and maxillofacial surgery department of Ehime University Hospital. We divided them into two groups: radiotherapy alone (24 cases) and chemoradiotherapy (23 cases). The patients in the radiotherapy group underwent irradiation of 32.6 +/- 5.0 Gy (mean +/- SD). The patients in the chemoradiotherapy group received a low-dose fraction of cisplatin (8 mg/mm2/day, 5 days a week; total dose: 139.4 +/- 67.1 mg) and 5-fluorouracil (300 mg/mm2/day, 5 days a week; total dose: 5,900 +/- 1,839.8 mg) combined with simultaneous irradiation of 31.0 +/- 3.2 Gy. None of the 24 patients had a complete response to radiotherapy alone and 12 (50%) had a partial response. Six (26%) of the 23 patients had a complete response to chemoradiotherapy and 12 (52%) had a partial response. The primary control rate (82.6%) to chemoradiotherapy was higher than that (67.5%) to radiotherapy alone although no significant difference was found. The 5-year survival rate was 64.3% in the radiotherapy group and 62.8% in the chemoradiotherapy group. The findings of the present study suggest that while the combination of radiation and cisplatin/5-fluorouracil in neoadjuvant therapy for oral cancer may not bring a significant benefit to improve survival rate, the primary local control rate is improved in comparison with radiotherapy alone.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

Surface osteosarcoma: 2 case reports.

Surface osteosarcoma of the jaw bone is extremely rare, and it differs from the central type in its clinicopathologic features. This type of osteosarcoma generally shows low-grade malignancy, grows slowly, metastasizes less often, and the prognosis is better than that of the central type. We report 2 cases of surface osteosarcoma of the jaw bone, and discuss some clinical important issues.

Adolescent↗

PubMedDate not supplied

Infiltration of tumor-associated macrophages in human oral squamous cell carcinoma.

Tumor-associated macrophages (TAMs) have been shown to display both positive and negative effects on tumor growth of various cancer. In this study, TAMs were immunohistochemically labeled using CD68 antibody in 82 oral cancer. Macrophage index (MI) were analyzed in association with clinical and pathological factors, intratumoral microvessel density (IMVD) and angiogenic factors including VEGF and TP. Significantly higher number of CD68-positive cells was noted in oral cancer. TAM expressions were significantly associated with stages of invasion, IMVD, and angiogenic factors. These findings suggest that TAMs possibly play a role in angiogenesis during oral cancer progression.

Antigens, CD↗