Arimichi Takabayashi

Bio: Arimichi Takabayashi is an academic researcher from Kyoto University. The author has contributed to research in topics: Cancer & Antigen. The author has an hindex of 25, co-authored 64 publications receiving 3892 citations. Previous affiliations of Arimichi Takabayashi include University of Helsinki & Ehime University.

Familial gastrointestinal stromal tumours with germline mutation of the kit gene

Abstract: nature genetics volume 19 august 1998 323 Gastrointestinal stromal tumour (GIST) is the most common mesenchymal tumour of the human gastrointestinal tract. Most GISTs are solitary, and gain-offunction mutations of the KIT protooncogene have been found in these tumours1. We report here a family with multiple GISTs: affected members all have a KIT mutation occurring between the transmembrane and tyrosine kinase domains, which is also the region where mutations have been found in solitary GISTs (ref. 1). The KIT mutation in this family was detected not only in tumours but also in leukocytes, indicating that GISTs constitute a familial cancer syndrome2. Development of multiple GISTs was found in a 60-year-old Japanese woman (Fig. 1a, case 5). Her nephew (case 10) also suffered from multiple benign GISTs. Analysis of the family pedigree revealed many family members suffering from symptoms attributable to development of multiple GISTs (Fig. 1a), including case 9 (a niece of case 5) who underwent surgery for benign and malignant GISTs. The benign GISTs obtained from cases 5, 9 and 10, and the malignant GIST from case 9, all expressed the KIT protein (Fig. 1b–e). DNA was extracted from paraffin-embedded specimens of the tumours3, and the mutation was investigated using single-strand conformation polymorphism analysis4 (SSCP). SSCP of tumours from cases 5 and 10 showed wild-type and mutant bands at exon 11 (Fig. 1f). Direct sequencing of the mutant bands of exon 11 showed deletion of one of two consecutive valine residues (codon 559 and 560, GTTGTT) which are located between the transmembrane and tyrosine kinase domains. Unfortunately, DNA samples suitable for SSCP and direct sequencing were not obtained from tumours of case 9. Next, we obtained DNA from peripheral leukocytes of cases 5 and 10 and their family members. The valine deletion was detected in leukocyte DNA from cases 5, 10 and 15, but not in DNA from other family members. Case 15 is 22 years old and has so far had no abdominal symptoms. We investigated the function of the mutant KIT protein by introducing an analogous mutation into mouse Kit cDNA and transfecting it into the interleukin-3 (IL-3)-dependent Ba/F3 mouse lymphoid cell line1,5–7. Evidence was found for the constitutive phosphorylation and kinase Familial gastrointestinal stromal tumours with germline mutation of the KIT gene

CD4+CD25+ regulatory T cells in patients with gastrointestinal malignancies: possible involvement of regulatory T cells in disease progression.

Abstract: BACKGROUND Active suppression by CD4+CD25+ regulatory T cells plays an important role in the down-regulation of the response of T cells to foreign and self antigens. Experimental tumor models in mice revealed that regulatory T cells inhibit antitumor immune responses. The purpose of the current study was to demonstrate the possible involvement of CD4+CD25+ regulatory T cells in immune system impairment in patients with gastrointestinal malignancies. METHODS The phenotypes of lymphocytes, particularly those of CD4+CD25+ T cells, were analyzed in peripheral blood in 149 patients with gastrointestinal malignancies and in ascites in 7 patients with peritoneal dissemination. In addition, cytokine production after in vitro stimulation was examined in CD4+CD25+ and CD4+CD25− T cells isolated from patients with malignant disease. RESULTS Compared with healthy volunteers, patients with gastrointestinal malignancies had a higher proportion of CD4+CD25+ T cells in peripheral blood, due to the presence of a drastically smaller number of CD4+CD25− T cells. Among patients with gastric carcinoma, those with higher percentages of CD4+CD25+ T cells had a poorer prognosis than did those with lower percentages. CD4+CD25+ T cells also were present in greater proportions in ascites from patients who had advanced-stage disease with peritoneal dissemination. Isolated CD4+CD25+ T cells from patients with malignant disease produced interleukin (IL)-4 and IL-10 but not IL-2 or interferon-γ; these cells also inhibited cytokine production by CD4+CD25− T cells after in vitro stimulation. CONCLUSIONS The relative increase in CD4+CD25+ regulatory T cells may be related to immunosuppression and tumor progression in patients with gastrointestinal malignancies. This finding suggests that the use of immunomodulatory therapy to treat patients with gastrointestinal malignancies may be an effective strategy. Cancer 2003;98:1089–99. © 2003 American Cancer Society. DOI 10.1002/cncr.11618

SMAD4-deficient intestinal tumors recruit CCR1+ myeloid cells that promote invasion

Abstract: Inactivation of TGF-beta family signaling is implicated in colorectal tumor progression. Using cis-Apc(+/Delta716) Smad4(+/-) mutant mice (referred to as cis-Apc/Smad4), a model of invasive colorectal cancer in which TGF-beta family signaling is blocked, we show here that a new type of immature myeloid cell (iMC) is recruited from the bone marrow to the tumor invasion front. These CD34(+) iMCs express the matrix metalloproteinases MMP9 and MMP2 and the CC-chemokine receptor 1 (CCR1) and migrate toward the CCR1 ligand CCL9. In adenocarcinomas, expression of CCL9 is increased in the tumor epithelium. By deleting Ccr1 in the background of the cis-Apc/Smad4 mutant, we further show that lack of CCR1 prevents accumulation of CD34(+) iMCs at the invasion front and suppresses tumor invasion. These results indicate that loss of transforming growth factor-beta family signaling in tumor epithelium causes accumulation of iMCs that promote tumor invasion.

Pivotal role of CXCR3 in melanoma cell metastasis to lymph nodes.

Abstract: Chemokines and their receptors play key roles in leukocyte trafficking and are also implicated in cancer metastasis to specific organs. Here we show that mouse B16F10 melanoma cells constitutively express chemokine receptor CXCR3, and that its ligands CXCL9/Mig, CXCL10/IP-10, and CXCL11/I-TAC induce cellular responses in vitro, such as actin polymerization, migration, invasion, and cell survival. To determine whether CXCR3 could play a role in metastasis to lymph nodes (LNs), we constructed B16F10 cells with reduced CXCR3 expression by antisense RNA and investigated their metastatic activities after s.c. inoculations to syngeneic hosts, C57BL/6 mice. The metastatic frequency of these cells to LNs was markedly reduced to approximately 15% (P < 0.05) compared with the parental or empty vector-transduced cells. On the other hand, pretreatment of mice with complete Freund's adjuvant increased the levels of CXCL9 and CXCL10 in the draining LNs, which caused 2.5-3.0-fold increase (P < 0.05) in the metastatic frequency of B16F10 cells to the nodes with much larger foci. Importantly, such a stimulation of metastasis was largely suppressed when CXCR3 expression in B16F10 cells was reduced by antisense RNA or when mice were treated with specific antibodies against CXCL9 and CXCL10. We also demonstrate that CXCR3 is expressed on several human melanoma cell lines as well as primary human melanoma tissues (5 of 9 samples tested). These results suggest that CXCR3 inhibitors may be promising therapeutic agents for treatment of LN metastasis, including that of melanoma.

Cancer-related inflammation.

Abstract: The mediators and cellular effectors of inflammation are important constituents of the local environment of tumours. In some types of cancer, inflammatory conditions are present before a malignant change occurs. Conversely, in other types of cancer, an oncogenic change induces an inflammatory microenvironment that promotes the development of tumours. Regardless of its origin, 'smouldering' inflammation in the tumour microenvironment has many tumour-promoting effects. It aids in the proliferation and survival of malignant cells, promotes angiogenesis and metastasis, subverts adaptive immune responses, and alters responses to hormones and chemotherapeutic agents. The molecular pathways of this cancer-related inflammation are now being unravelled, resulting in the identification of new target molecules that could lead to improved diagnosis and treatment.

Flavonoid antioxidants: chemistry, metabolism and structure-activity relationships.

Abstract: Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.

Microenvironmental regulation of metastasis

Abstract: Metastasis is a multistage process that requires cancer cells to escape from the primary tumour, survive in the circulation, seed at distant sites and grow. Each of these processes involves rate-limiting steps that are influenced by non-malignant cells of the tumour microenvironment. Many of these cells are derived from the bone marrow, particularly the myeloid lineage, and are recruited by cancer cells to enhance their survival, growth, invasion and dissemination. This Review describes experimental data demonstrating the role of the microenvironment in metastasis, identifies areas for future research and suggests possible new therapeutic avenues.