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Biomedical subjects

Masakazu Toi

Publications and source records attributed to Masakazu Toi.

At least 37 records · Page 2Linked to original sources
PubMed2005

Targeting of nuclear factor kappaB Pathways by dehydroxymethylepoxyquinomicin, a novel inhibitor of breast carcinomas: antitumor and antiangiogenic potential in vivo.

We previously designed and synthesized the new nuclear factor kappaB (NF-kappaB) inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) derived from the structure of the antibiotic epoxyquinomicin C. We looked into the effect of DHMEQ on cellular phenotypes and tumor growth in mice injected with human breast carcinoma cell line MDA-MB-231 or MCF-7. In estrogen-independent breast adenocarcinoma cell line MDA-MB-231, NF-kappaB is constitutively activated. The addition of DHMEQ (10 microg/mL) completely inhibited the activated NF-kappaB for at least 8 hours. On the other hand, NF-kappaB is not activated in estrogen-dependent MCF-7 cells. In this cell line, DHMEQ completely inhibited the tumor necrosis factor-alpha-induced activation of NF-kappaB. DHMEQ did not inhibit the degradation of IkappaB but inhibited the nuclear translocation of NF-kappaB by both p65/p50 and RelB/p52 pathways. MDA-MB-231 cells secrete interleukin (IL)-6 and IL-8 without stimulation, and DHMEQ decreased the secretion levels of both cytokines. When MDA-MB-231 or MCF-7 cells were stimulated by tumor necrosis factor-alpha, the inhibitory effects of DHMEQ were still maintained. I.p. administration of DHMEQ (thrice a week) significantly inhibited the tumor growth of MDA-MB-231 (12 mg/kg) or MCF-7 (4 mg/kg) in severe combined immunodeficiency mice. No toxicity was observed during the experiment, including the loss of body weight. An immunohistological study on resected MCF-7 tumors showed that DHMEQ inhibited angiogenesis and promoted apoptosis. Furthermore, in Adriamycin-resistant MCF-7 cells highly expressing multidrug resistance gene-1, DHMEQ also exhibited the above capability, including down-regulation of IL-8. Thus, DHMEQ might be a potent drug for the treatment of various breast carcinomas by inhibiting the NF-kappaB activity.

Angiogenesis Inhibitors↗
PubMed2005

Clinical significance of estrogen receptor beta in breast cancer.

Ever since the estrogen receptor (ER) beta was discovered in 1996, we have been trying to determine its value as a prognostic and/or predictive factor in breast cancer and its potential as a novel target for pharmacological intervention. Recent progress in cellular experiments has shown that ERbeta works as counter partner of ERalpha through inhibition of the transactivating function of ERalpha by heterodimerization, distinct regulation on several specific promoters by ERalpha or ERbeta, and ERbeta-specific regulated genes which are probably related to its anti-proliferative properties. Accumulated data from protein studies in breast cancer tissues indicate that positive expression of ERbeta appears to correlate with a favorable prognosis. Although the number of studies is small, a positive response to tamoxifen treatment is observed in both ERalpha- and ERbeta-positive populations. The significance of ERbeta2/cx, a splicing variant of ERbeta, remains controversial and needs to be analyzed in further studies. We postulate that a combined evaluation of ERbetacx with progesterone receptor may help the stratification of ERalpha-positive breast cancer. Epidemiological studies of hormone replacement therapy and isoflavone (genistein) consumption indicate the possible contribution of ERbeta-specific signaling in breast cancer prevention. A selective estrogen receptor modulator, which works as an antagonist of ERalpha and an agonist of ERbeta, may be a promising chemo-preventive treatment.

Breast Neoplasms↗
PubMed2005

Trastuzumab: updates and future issues.

Trastuzumab has had an enormous impact on the clinical management of breast cancer: the survival of Her-2-positive metastatic breast cancer patients has improved significantly and tumor Her-2 status has been built into the decision-making tree for primary breast cancer patients. Several pioneering studies have shown that trastuzumab-combined chemotherapy elicits high levels of pathological complete response in the neoadjuvant setting. Currently, therefore, a more precise understanding of the mechanisms of therapeutic response is needed so that trastuzumab-based therapies can be optimized more individually. It might also be important to investigate, with greater depth, the interaction between the Her-axis and the hormone-axis. This short review describes and discusses these topics.

Antibodies, Monoclonal↗
PubMed2005

A Japanese phase I study of continuous oral capecitabine in patients with malignant solid tumors.

BACKGROUND: This study aimed to evaluate the tolerability and pharmacokinetics of capecitabine, given twice daily for 6 weeks without interruption, and to identify the maximum tolerated dose (MTD) and the suggested phase II schedule. METHODS: The initial dose of capecitabine was 251 mg/m2 twice daily, without interruption, and a dose escalation schedule was planned according to a modified Fibonacci scheme. Patients received oral capecitabine twice daily for at least 6 weeks unless grade 3 or 4 toxicity was observed. Blood and urine samples were collected for pharmocokinetic analysis on days 1 and 15. RESULTS: Sixteen patients with malignant solid tumors (seven breast, seven colorectal, and two gastric) were enrolled, all of whom were evaluable. Among 4 patients treated with capecitabine 1255 mg/m2 twice daily, one experienced grade 4 hemorrhagic gastric ulcer and one experienced grade 3 skin toxicity. Consequently, this dose was defined as the MTD, and gastrointestinal and cutaneous effects were identified as dose-limiting toxicities. There was no grade 3/4 diarrhea at any dose level. There was also no grade 4 hematologic toxicity at doses below the MTD, and there were no treatment-related deaths. Two patients with breast cancer had partial responses, at capecitabine doses of 502 mg/m2 and 1255 mg/m2, twice daily. Pharmacokinetic data show that high concentrations of doxifluridine (5'-DFUR) occur in tumor cells within 2 h after administration of capecitabine. CONCLUSION: The MTD of continuous oral capecitabine over 6 weeks was 1255 mg/m2 twice daily. Because of the higher occurrence of skin disorders reported in this study with a continuous treatment regimen, an intermittent treatment regimen of 828 mg/m2, administered twice daily for 3 weeks, followed by a 1-week rest period, was recommended for phase II studies. This regimen is being evaluated in phase II studies in Japanese patients with gastric, colorectal, and breast cancers.

Administration, Oral↗
PubMed2005

Thymidine phosphorylase (platelet-derived endothelial-cell growth factor) in cancer biology and treatment.

Thymidine phosphorylase (TP) is often induced in the tumour microenvironment by physiological and chemical stress. Its induction protects cells from apoptosis and helps cell survival by stimulating nucleoside metabolism and angiogenesis. Chemotherapy often upregulates TP, which acts in cell rescue; this result indicates that TP is a crucial therapeutic target. Clinical trials for metastatic diseases have shown that TP-targeting chemotherapy with fluorouracil derivatives greatly improves the effectiveness of conventional chemotherapy for not only response but also prognosis. This new idea, the improvement of TP-inducible therapy with TP-targeting therapy, should be further investigated for early disease states, and inhibitors of TP warrant extensive investigation.

Apoptosis↗
PubMed2005

Angiogenic inhibitors: a new therapeutic strategy in oncology.

Angiogenesis is a multistep, complex and tightly regulated process that is necessary for tumor growth and metastasis. Based on data of preclinical models, several antiangiogenic compounds has been shown to modify activated tumor endothelium, which suggests that these compounds can improve cytotoxic drug delivery. Such agents have entered clinical trials as single agents or in combination with cytotoxic drugs, and have shown promising antitumor activity. The pharmacodynamic and pharmacokinetic characteristics of antiangiogenic drugs are reviewed here. Most of the early clinical testing of these agents was conducted in patients with advanced disease resistant to standard therapies. Phase III trials compared the efficacy of standard chemotherapy alone with standard chemotherapy in combination with an experimental angiogenesis inhibitor. Although some of these studies were negative or controversial, recent studies validated in large clinical trials with an anti-vascular endothelial growth factor antibody demonstrated significant clinical benefit and renewed enthusiasm for this therapeutic strategy. This review describes the clinical studies of antiangiogenic agents and highlights the challenges related to choosing appropriate strategies for the selection of patients, study design and choice of appropriate endpoints for the studies' development.

Angiogenesis Inhibitors↗
PubMed2005

Nuclear factor-kappaB inhibitors as sensitizers to anticancer drugs.

The cytotoxicity of chemotherapeutic agents is attributed to apoptosis. Acquired resistance to the effects of chemotherapy has emerged as a significant impediment to effective cancer therapy. One feature that cytotoxic treatments of cancer have in common is their activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which regulates cell survival. NF-kappaB activation suppresses the apoptotic potential of chemotherapeutic agents and contributes to resistance. What evidence is there that inhibitors of NF-kappaB might promote apoptosis in cancer cells and can NF-kappaB inhibitors be used to overcome resistance to chemotherapeutic agents?

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Translational research in breast cancer.

Translational research (TR) involves both the development of novel diagnostics and novel therapeutics. These two major developmental areas are often associated with each other and these associations often bring new paradigms in the management of cancer patients. For example, the development of trastuzumab-based treatments has been conducted in harmony with the development of new methodologies to assess the expression of the Her-2 gene or protein, and from this, a therapeutic modality was established for breast cancer patients as a novel and individualized treatment system. TR covers a broad spectrum, from diagnosis to treatment, and it seems to act as a catalyst for developing novel paradigms. Therefore, it is crucial to conduct TR in clinical trials, in particular, prospective clinical trials. In this regard, TR can accelerate the development of new methodologies and increase trial efficiency. In this review, we describe the importance of TR, particularly that related to novel therapeutics.

Antineoplastic Agents↗
PubMed2005

Interim analysis of a phase II trial of cyclophosphamide, epirubicin and 5-fluorouracil (CEF) followed by docetaxel as preoperative chemotherapy for early stage breast carcinoma.

PURPOSE: A single-arm phase II multicenter trial of the combination of cyclophosphamide (C), epirubicin (E), and 5-fluorouracil (F) followed by docetaxel as neoadjuvant chemotherapy is being conducted by the Japan Breast Cancer Research Group. This report describes an interim analysis of the clinical response and safety of 79 patients who finished preoperative chemotherapy and surgery. PATIENTS AND METHODS: Patients with operable breast cancer received C at 500 mg/m2, E at 100 mg/m2, and F at 500 mg/m2 every 21 days for 4 cycles followed by docetaxel at 75 mg/m2 every 21 days for 4 cycles. RESULTS: Of the 79 patients evaluable for analysis the median age was 46 years (28-59), and 61 patients (77.2%) had T2 tumors. A total of 312 of 316 (98.7%) cycles of CEF and 296 of 312 (94.9%) cycles of docetaxel were administered. Average total cumulative dose was 92% and 95% for CEF and docetaxel, respectively. The rate and grade of edema, neuropathy, arthralgia and myalgia were higher with docetaxel than with CEF. The overall clinical response rate was 70.9%. Breast conserving surgery was performed in 31 of 42 patients (73.8%) with a base-line tumor size of more than 3 cm. CONCLUSIONS: Interim data suggest that CEF followed by docetaxel is an active and tolerable neoadjuvant chemotherapy regimen. A final analysis is planned for 2005.

Adult↗
PubMed2005

Reducing the global breast cancer burden: the importance of patterns of care research.

Breast cancer treatment guidelines are not uniformly followed in clinical practice, with evidence for substantial variations in treatment patterns, quality of care, and patient outcomes among and within countries. The factors that drive treatment decisions are unclear. Furthermore, the impact of different treatment strategies on survival is poorly understood outside the clinical trial setting. Sources of patterns of care information often have limitations in completeness, quality, timeliness of reporting, and relevance to the larger population. Patterns of care studies frequently lack details on cancer stage at diagnosis, tumor biology, and treatment received. It is difficult to compare data between studies and/or track changes over time because of variations in data sources and collection techniques. Thus, the design and implementation of a global registry is sorely needed in order to prospectively evaluate worldwide patterns of care and outcomes in patients with breast cancer. Components of this registry should include random selection of centers of variable practice settings in multiple countries and accurate and rapid data reporting at prestudy and follow-up timepoints. Data collected would include tumor and demographic factors, staging information, treatment rendered, and survival. Variables that influenced the treatment selected would be assessed. This unique international effort would allow the development of strategies to improve diagnostic and treatment-related standards of care and survival outcomes, thus reducing the breast cancer burden worldwide.

Breast Neoplasms↗
PubMed2005

Importance of thymidine phosphorylase expression in tumor stroma as a prognostic factor in patients with advanced colorectal carcinoma.

Thymidine phosphorylase (TP) is a unique enzyme involved not only in angiogenesis, but in 5-fluorouracil (5-FU) metabolism as well. TP is produced by both tumor and stromal cells. The aim of this study was to reveal the clinical implication of TP localization in tumor tissues. Advanced colorectal cancer specimens (n=97) were prepared for immunohistochemical staining using monoclonal antibodies against TP, p53, vascular endothelial growth factor (VEGF), factor VIII, CD68 and thymidylate synthase (TS). Clinicopathological factors and the clinical prognosis were examined for each indicator. High tumor TP expression and high stromal TP expression were observed in 38% (36/95 cases) and 49% (47/95 cases) of the cases, respectively. High tumor TP expression tended to correlate with microvessel density (MVD) (p=0.0511). Among patients who underwent curative resection, those with high stromal TP expression had a favorable prognosis (p=0.0127). High stromal TP status was also a strong prognostic factor in the group receiving adjuvant 5-FU derivatives (p=0.0222). TP produced by tumor cells has a stimulatory effect on tumor angiogenesis, while that produced by stromal cells plays an entirely different role. The latter may enhance the anticancer effect of 5-FU via its catalyzed function.

Adult↗
PubMed2005

Cost-effectiveness of letrozole versus tamoxifen as first-line hormonal therapy in treating postmenopausal women with advanced breast cancer in Japan.

The objective of this study is to evaluate the cost-effectiveness of letrozole compared with tamoxifen as first-line therapy in post-menopausal women with advanced breast cancer in Japan. A Markov analytical model was developed to estimate life-year (LY) expectancies, using key transition probabilities obtained from the results of a multinational phase III trial, a literature review and a Japanese medical expert panel. Direct medical costs were estimated, from the payer's perspective, using the expected resource utilization provided by the expert panel, the medical fee table and drug tariff under the national health insurance system. The expected overall life-years (LYs) obtained were 3.68 years for letrozole arm and 3.09 years for tamoxifen arm, showing incremental LYs of 0.59 years in patients receiving letrozole. The total expected costs were 3,644,588 yen (33,133 US dollars) for letrozole arm and 3,322,111 yen (30,201 US dollars) for tamoxifen arm, resulting in a mean incremental cost-effectiveness ratio (ICER) of 546,571 yen (4,969 US dollars) per life-year gained, while the 5 th percentile of ICER showed letrozole dominating tamoxifen and the 95th percentile was 2,310,593 yen (21,005 US dollars). The results suggest that letrozole is a clinically beneficial and cost-effective treatment option when compared with tamoxifen in first-line therapy for advanced breast cancer in Japan.

Aged↗
PubMed2005

Enhancement of the caspase-independent apoptotic sensitivity of pancreatic cancer cells by DHMEQ, an NF-kappaB inhibitor.

The effects of the nuclear factor (NF)-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), combined with tumor necrosis factor (TNF)-alpha were evaluated in PK-8 pancreatic cancer cells. NF-kappaB was activated by TNF-alpha; however, the administration of DHMEQ abrogated its transcriptional activity. The addition of DHMEQ to TNF-alpha markedly induced apoptosis in PK-8 cells with down-regulation of anti-apoptotic c-FLIP and survivin. Combined treatment significantly suppressed cell viability in vitro, and the anti-tumor effect of DHMEQ was also significant in vivo. We investigated the apoptosis signaling pathway involved in these cell killing effects. Truncated Bid was produced by activated caspase-8, and the subsequent depolarization of the mitochondrial membrane potential (Delta Psi m) peaked at 6 h. Then, the activity of caspase-3 was up-regulated 8-fold. Z-VAD-fmk (a pan-caspase inhibitor) perfectly inhibited the up-regulation of caspase-3 but failed to reverse the cell viability. The above findings indicated that the growth inhibitory effect of combined treatment largely depended on mitochondria-associated caspase-independent apoptosis. The intracellular behavior of apoptosis-inducing factor (AIF) following depolarization of Delta Psi m suggested that AIF executed such a caspase-independent apoptosis. Interestingly, caspase-dependent apoptosis appeared within 6 h, whereas the caspase-independent apoptosis lagged. Thus, the addition of DHMEQ to TNF-alpha was capable of inducing caspase-independent apoptosis in pancreatic cancer cells. Once caspase-independent apoptosis was induced, the apoptosis demonstrated powerful cytotoxicity. Therefore, DHMEQ in combination with TNF-alpha may be a promising treatment for pancreatic cancer.

Apoptosis↗
PubMed2004

Immunodetection and quantification of vascular endothelial growth factor receptor-3 in human malignant tumor tissues.

Vascular endothelial growth factor receptor-3 (VEGFR-3) and its ligands, vascular endothelial growth factor-C (VEGF-C) and -D (VEGF-D), are the major molecules involved in developmental and pathological lymphangiogenesis. Here we describe for the first time the development of a specific indirect enzyme-linked immunosorbent assay (ELISA) for the quantification of VEGFR-3 in different human cell and tissue lysates. A combination of the goat polyclonal anti-VEGFR-3 antibody and the mouse monoclonal anti-human VEGFR-3 antibody was used. The assay was highly sensitive and reproducible with a detection range of 0.2-25 ng/ml. The assay was specific for VEGFR-3, with no cross-reactivity to VEGFR-1 or VEGFR-2. Complex formation with VEGF-C and VEGF-D had no effect on the sensitivity of the assay. The VEGFR-3 concentration in the lysates of cultured human dermal microvascular endothelial cells was 14-fold higher than in the lysates from human umbilical vein endothelial cells. In human kidney, breast, colon, gastric and lung cancer tissues the protein levels of VEGFR-3 were in the range of 0.6-16.7 ng/mg protein. Importantly, the level of VEGFR-3 protein detected in the ELISA correlated significantly with the number of VEGFR-3 positive vessels observed in histochemical sections, suggesting that the ELISA assay may be a reliable surrogate of measuring VEGFR-3-positive vessel density. The protein levels of VEGFR-3 in 27 renal cell carcinoma samples had a significant correlation with the levels of VEGF-C (p<0.001), or biological active, free VEGF-A (p<0.0001), but not with VEGFR-1 or total VEGF-A. This assay provides a useful tool for the investigations of the expression levels of VEGFR-3 in physiological and pathological processes, particular in cancer and in lymphangiogenesis-related disease.

Animals↗
PubMed2004

Quantification of vascular endothelial growth factor-C (VEGF-C) by a novel ELISA.

Lymphangiogenesis plays an important role in several normal and pathological conditions such as wound healing, inflammation or metastasis formation in several malignancies. VEGF-C and VEGF-D are important and specific regulatory factors for lymphatic endothelial proliferation and lymphangiogenesis. In order to develop a highly sensitive and specific detection system for VEGF-C, we produced soluble binding proteins and antibodies for a microtiterplate-based assay. Here we describe a specific enzyme-linked immunosorbent assay (ELISA) for the measurement of human, rat and murine VEGF-C. The different antibodies developed against human and rat VEGF-C could be combined to detect processed and partially processed VEGF-C in a specific way. The ELISA was able to detect human and rat VEGF-C with a minimum detection limit of 100 pg/ml. The assay did not show any cross-reactivity with the related protein VEGF-D. Furthermore, complex formation with its soluble receptors VEGFR-2 and VEGFR-3 did not restricted the sensitivity of the assay. Using this assay, VEGF-C was measured in supernatants and lysates of different cell types and in tumour tissue samples of murine, rat and human origin. Cell lines secrete VEGF-C in very low amounts (<1 ng/ml) whereas VEGF-C transfected cells can secrete up to 50 ng/ml VEGF-C into the supernatant. In human tumour tissue samples VEGF-C was detected in some carcinomas in the low protein range. This ELISA will be a useful tool for investigations concerning the physiological function of VEGF-C in lymphangiogenesis under normal and pathophysiological conditions.

Animals↗
PubMed2004

Current status of antibody therapy for breast cancer.

Antibody therapy with trastuzumab has greatly impacted breast cancer treatment. Combination treatment with trastuzumab is regarded currently as a first-line therapy for metastatic breast cancers that overexpress Her-2. It has become routine practice to examine the status of Her-2 expression in primary tumors. The impact of this therapy might be as great as that of endocrine therapy from a historical point of view. A number of new approaches using trastuzumab for seeking individualized treatment are being tested in current clinical trials. We reviewed recent advances in trastuzumab treatment and discuss the future of antibody therapy for breast cancer.

Antibodies, Monoclonal↗