Takaomi Okawa

Publications of Takaomi Okawa

• A subpopulation of mouse esophageal basal cells has properties of stem cells with the capacity for self-renewal and lineage specification.

  Authors: Jiri Kalabis, Kenji Oyama, Takaomi Okawa, Hiroshi Nakagawa, Carmen Z Michaylira, Douglas B Stairs, Jose-Luiz Figueiredo, Umar Mahmood, J Alan Diehl, Meenhard Herlyn, Anil K Rustgi

  The Journal of clinical investigation. 01/2009; 118(12):3860-9.

  The esophageal epithelium is a prototypical stratified squamous epithelium that exhibits an exquisite equilibrium between proliferation and differentiation. After basal cells proliferate, theyThe esophageal epithelium is a prototypical stratified squamous epithelium that exhibits an exquisite equilibrium between proliferation and differentiation. After basal cells proliferate, they migrate outward toward the luminal surface, undergo differentiation, and eventually slough due to apoptosis. The identification and characterization of stem cells responsible for the maintenance of the esophageal epithelium remains elusive. Here, we employed Hoechst dye extrusion and BrdU label-retaining assays to identify in mice a potential esophageal stem cell population that localizes to the basal cell compartment. The self-renewing capacity of this population was characterized using a clonogenic assay and a 3D organotypic culture model. The putative esophageal stem cells were also capable of epithelial reconstitution in vivo in direct esophageal epithelial injury models. In both the 3D organotypic culture and direct mucosal injury models, the putative stem cells gave rise to undifferentiated and differentiated cells. These studies therefore provide a basis for understanding the regenerative capacity and biology of the esophageal epithelium when it is faced with injurious insults.

• Localization of FAK is related with colorectal carcinogenesis.

  Authors: Toshihiro Murata, Yoshio Naomoto, Tomoki Yamatsuji, Takaomi Okawa, Yasuhiro Shirakawa, Mehmet Gunduz, Tetsuji Nobuhisa, Munenori Takaoka, Mehmet Sirmali, Motowo Nakajima, Yuko Ohno, Noriaki Tanaka

  International journal of oncology. 05/2008; 32(4):791-6.

  Focal adhesion kinase (FAK) is an important mediator functioning between cells and the extracellular matrix and is closely related with the integrin-signaling pathway. FAK has been reported to beFocal adhesion kinase (FAK) is an important mediator functioning between cells and the extracellular matrix and is closely related with the integrin-signaling pathway. FAK has been reported to be involved in the proliferation, differentiation and apoptosis of cells. To date, no report has demonstrated the involvement of FAK in the carcinogenesis of the digestive tract. Therefore, we examined colorectal, esophageal, pancreatic and mammary cancers for expression of FAK and Phospho (P)-FAK by immunohistochemistry. Strong expression of FAK in the cytoplasm was detected in all 4 tumor types and expressions of FAK and P-FAK increased as the degree of cell differentiation became higher in colorectal and esophageal carcinomas. Interestingly P-FAK expression was confined to the nuclei, which was an unexpected result. No previous report of such a finding has been published for gastrointestinal cancer. All four of the organs investigated in the present study showed P-FAK expression in the nuclei, suggesting an association between FAK activation and abnormal cell proliferation. We also performed immunostaining of P-FAK in cell lines to examine the significance of its experience in the nuclei. However, unlike clinical specimens, the cell lines did not show P-FAK expression in the nuclei. Moreover, the injection of cancer cells into the peritoneal cavity of mice also failed to demonstrate P-FAK expression in the nuclei. These results may be related with the function of carrier proteins of FAK such as Hic-5 and Zyxin, which are found only in humans. Taken together, FAK and P-FAK are involved in the carcinogenesis of digestive organs.

• The functional interplay between EGFR overexpression, hTERT activation, and p53 mutation in esophageal epithelial cells with activation of stromal fibroblasts induces tumor development, invasion, and differentiation.

  Authors: Takaomi Okawa, Carmen Z Michaylira, Jiri Kalabis, Douglas B Stairs, Hiroshi Nakagawa, Claudia D Andl, Cameron N Johnstone, Andres J Klein-Szanto, Wafik S El-Deiry, Edna Cukierman, Meenhard Herlyn, Anil K Rustgi

  Genes & development. 12/2007; 21(21):2788-803.

  Esophageal cancer is a prototypic squamous cell cancer that carries a poor prognosis, primarily due to presentation at advanced stages. We used human esophageal epithelial cells as a platform toEsophageal cancer is a prototypic squamous cell cancer that carries a poor prognosis, primarily due to presentation at advanced stages. We used human esophageal epithelial cells as a platform to recapitulate esophageal squamous cell cancer, thereby providing insights into the molecular pathogenesis of squamous cell cancers in general. This was achieved through the retroviral-mediated transduction into normal, primary human esophageal epithelial cells of epidermal growth factor receptor (EGFR), the catalytic subunit of human telomerase (hTERT), and p53(R175H), genes that are frequently altered in human esophageal squamous cell cancer. These cells demonstrated increased migration and invasion when compared with control cells. When these genetically altered cells were placed within the in vivo-like context of an organotypic three-dimensional (3D) culture system, the cells formed a high-grade dysplastic epithelium with malignant cells invading into the stromal extracellular matrix (ECM). The invasive phenotype was in part modulated by the activation of matrix metalloproteinase-9 (MMP-9). Using pharmacological and genetic approaches to decrease MMP-9, invasion into the underlying ECM could be suppressed partially. In addition, tumor differentiation was influenced by the type of fibroblasts within the stromal ECM. To that end, fetal esophageal fibroblasts fostered a microenvironment conducive to poorly differentiated invading tumor cells, whereas fetal skin fibroblasts supported a well-differentiated tumor as illustrated by keratin "pearl" formation, a hallmark feature of well-differentiated squamous cell cancers. When inducible AKT was introduced into fetal skin esophageal fibroblasts, a more invasive, less-differentiated esophageal cancer phenotype was achieved. Invasion into the stromal ECM was attenuated by genetic knockdown of AKT1 as well as AKT2. Taken together, alterations in key oncogenes and tumor suppressor genes in esophageal epithelial cells, the composition and activation of fibroblasts, and the components of the ECM conspire to regulate the physical and biological properties of the stroma.

• Translocation of heparanase into nucleus results in cell differentiation.

  Authors: Tetsuji Nobuhisa, Yoshio Naomoto, Takaomi Okawa, Munenori Takaoka, Mehmet Gunduz, Takayuki Motoki, Hitoshi Nagatsuka, Hidetsugu Tsujigiwa, Yasuhiro Shirakawa, Tomoki Yamatsuji, Minoru Haisa, Junji Matsuoka, Junichi Kurebayashi, Motowo Nakajima, Shun'ichiro Taniguchi, Junji Sagara, Jian Dong, Noriaki Tanaka

  Cancer science. 05/2007; 98(4):535-40.

  We recently reported that heparanase, one of the extracellular matrix-degrading enzymes, which plays a critical role in cancer progression, is located not only in the cytoplasm but also in theWe recently reported that heparanase, one of the extracellular matrix-degrading enzymes, which plays a critical role in cancer progression, is located not only in the cytoplasm but also in the nucleus. Here we identified nuclear translocation of heparanase as a key step in cell differentiation. We applied an in vitro differentiation model of HL-60 cells with 12-0-tetradecanoylphorbol-13-acetate (TPA), in which nuclear translocation of heparanase was observed using immunohistochemical analysis. In this system, nuclear translocation of heparanase was abolished by inhibitors of heat shock protein 90 (HSP90), suggesting the involvement of HSP90 in translocation of heparanase. We further confirmed that overexpression of active form of heparanase induced differentiation of HL-60 cells, although the catalytic negative form of heparanase did not. Therefore we speculate that nuclear translocation of enzymatically active heparanase may be involved in cellular differentiation. Our results suggest that a novel function of heparanase upon cell differentiation would raise a potential new strategy for cancer therapy of promyeloid leukemia and other types of cancer.

• IGFBP-3 regulates esophageal tumor growth through IGF-dependent and independent mechanisms.

  Authors: Munenori Takaoka, Seok Hyun Kim, Takaomi Okawa, Carmen Z Michaylira, Douglas B Stairs, Cameron N Johnstone, Claudia D Andl, Ben Rhoades, James J Lee, Andres J P Klein-Szanto, Wafik S El-Deiry, Hiroshi Nakagawa

  Cancer biology & therapy. 05/2007; 6(4):534-40.

  Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophagealInsulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-Ras(V12)-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-1 from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.

• Heparanase promotes angiogenesis through Cox-2 and HIF1alpha.

  Authors: Yoshio Naomoto, Mehmet Gunduz, Munenori Takaoka, Takaomi Okawa, Esra Gunduz, Tetsuji Nobuhisa, Masahiko Kobayashi, Yasuhiro Shirakawa, Tomoki Yamatsuji, Ryutaro Sonoda, Junji Matsuoka, Noriaki Tanaka

  Medical hypotheses. 02/2007; 68(1):162-5.

  Heparanase has been given attention for its role in the invasion and metastasis of various cancers for years. We have also investigated and reported the role of heparanase in several human cancers,Heparanase has been given attention for its role in the invasion and metastasis of various cancers for years. We have also investigated and reported the role of heparanase in several human cancers, including gastric, esophageal and colon carcinomas. Other than the critical role of heparanase in tumor invasion and metastasis, it is also believed that heparanase is involved in angiogenesis, another feature of tumor progression which is complicatedly mediated by many molecules, including cyclooxygenese-2 (Cox-2). Thus, our recent study elucidated a possible relationship of heparanase with Cox-2 upon tumor angiogenesis. Based upon our study, three major transcription factor binding sites containing NF-kappaB, NF-IL-6 and CRE sites seemed to have a compensative and cooperative role in heparanase-induced Cox-2 upregulation. On the other hand, tumor hypoxia often occurs in most tumors and Cox-2-induced HIF1alpha overexpression has recently been shown in various cancers. Here we believe that heparanase may also be involved in tumor hypoxia through the induction of HIFalpha either directly or indirectly through the Cox-2 pathway. This hypothesis indicates a possible novel function of heparanase and its link to HIF1alpha and Cox-2, and therefore this function would give us a clue about potential new strategies for cancer therapy.

• Coordinated functions of E-cadherin and transforming growth factor beta receptor II in vitro and in vivo.

  Authors: Claudia D Andl, Brenton B Fargnoli, Takaomi Okawa, Mark Bowser, Munenori Takaoka, Hiroshi Nakagawa, Andres Klein-Szanto, Xianxin Hua, Meenhard Herlyn, Anil K Rustgi

  Cancer research. 11/2006; 66(20):9878-85.

  In epithelial cells, E-cadherin plays a key role in cell-cell adhesion, and loss of E-cadherin is a hallmark of tumor progression fostering cancer cell invasion and metastasis. To examine E-cadherinIn epithelial cells, E-cadherin plays a key role in cell-cell adhesion, and loss of E-cadherin is a hallmark of tumor progression fostering cancer cell invasion and metastasis. To examine E-cadherin loss in squamous cell cancers, we used primary human esophageal epithelial cells (keratinocytes) as a platform and retrovirally transduced wild-type and dominant-negative forms of E-cadherin into these cells. We found decreased cell adhesion in the cells expressing dominant-negative E-cadherin, thereby resulting in enhanced migration and invasion. To analyze which molecular pathway(s) may modulate these changes, we conducted microarray analysis and found up-regulation of transforming growth factor beta receptor II (TbetaRII) in the wild-type E-cadherin-overexpressing cells, which was confirmed by real-time PCR and Western blot analyses. To investigate the in vivo relevance of this finding, we analyzed tissue microarrays of paired esophageal squamous cell carcinomas and adjacent normal esophagus, and we could show a coordinated loss of E-cadherin and TbetaRII in approximately 80% of tumors. To determine if there may be an E-cadherin-dependent regulation of TbetaRII, we show the physical interaction of E-cadherin with TbetaRII and that this is mediated through the extracellular domains of E-cadherin and TbetaRII, respectively. In addition, TbetaRI is recruited to this complex. When placed in the context of three-dimensional cell culture, which reflects the physiologic microenvironment, TbetaRII-mediated cell signaling is dependent upon intact E-cadherin function. Our results, which suggest that E-cadherin regulates TbetaRII function, have important implications for epithelial carcinogenesis characterized through the frequent occurrence of E-cadherin and TbetaRII loss.

• Heparanase regulates esophageal keratinocyte differentiation through nuclear translocation and heparan sulfate cleavage.

  Authors: Masahiko Kobayashi, Yoshio Naomoto, Tetsuji Nobuhisa, Takaomi Okawa, Munenori Takaoka, Yasuhiro Shirakawa, Tomoki Yamatsuji, Junji Matsuoka, Takaaki Mizushima, Hironori Matsuura, Motowo Nakajima, Hiroshi Nakagawa, Anil Rustgi, Noriaki Tanaka

  Differentiation; research in biological diversity. 07/2006; 74(5):235-43.

  Heparanase is an endo-beta-glucuronidase that specifically cleaves heparan sulfate (HS) chains. Heparanase is involved in the process of metastasis and angiogenesis through the degradation of HSHeparanase is an endo-beta-glucuronidase that specifically cleaves heparan sulfate (HS) chains. Heparanase is involved in the process of metastasis and angiogenesis through the degradation of HS chains of the extracellular matrix and cell surface. Recently, we demonstrated that heparanase was localized in the cell nucleus of normal esophageal epithelium and esophageal cancer, and that its expression was correlated with cell differentiation. However, the nuclear function of heparanase remains unknown. To elucidate the role of heparanase in esophageal epithelial differentiation, primary human esophageal cells were grown in monolayer as well as organotypic cultures, and cell differentiation was induced. Expression of heparanase, HS, involucrin, and p27 was determined by immunostaining and Western blotting. SF4, a novel pharmacological inhibitor, was used to specifically inhibit heparanase activity. Upon esophageal cell differentiation, heparanase was translocated from the cytoplasm to the nucleus. Such translocation of heparanase appeared to be associated with the degradation of HS chains in the nucleus and changes in the expression of keratinocyte differentiation markers such as p27 and involucrin, whose induction was inhibited by SF4. Furthermore, these in vitro observations agreed with the expression pattern of heparanase, HS, involucrin, cytokeratin 13, and p27 in normal esophageal epithelium. Nuclear translocation of heparanase and its catalytic cleavage of HS may play a critical role in the differentiation of esophageal epithelial cells. Our study provides a novel insight into the role of heparanase in an essential differentiation process.

• Colonic interposition and supercharge for esophageal reconstruction.

  Authors: Yasuhiro Shirakawa, Yoshio Naomoto, Kazuhiro Noma, Kazufumi Sakurama, Toshio Nishikawa, Tetsuji Nobuhisa, Masahiko Kobayashi, Takaomi Okawa, Shinya Asami, Tomoki Yamatsuji, Minoru Haisa, Junji Matsuoka, Motohiko Hanazaki, Kiyoshi Morita, Takao Hiraki, Noriaki Tanaka

  Langenbeck's archives of surgery / Deutsche Gesellschaft für Chirurgie. 03/2006; 391(1):19-23.

  AIMS: We evaluated the techniques of colonic interposition and supercharge for esophageal reconstruction and discussed the main considerations related to these procedures. PATIENTS AND METHODS: InAIMS: We evaluated the techniques of colonic interposition and supercharge for esophageal reconstruction and discussed the main considerations related to these procedures. PATIENTS AND METHODS: In this study, we performed 51 esophageal reconstructions using colonic interposition. Twenty-eight of the 51 patients had synchronous or allochronic gastric malignancy. We selected colonic interposition for high anastomosis in 11 patients and also for esophageal bypass in 3 patients. This procedure was also selected to preserve gastric function in 5 patients. We recently performed the supercharge technique for colonic interposition in 41 patients. RESULTS: Despite the long duration and multistep nature of the operation procedure, no perioperative complications were noted. The patients returned to a good quality of life. The incidence of postoperative weight loss did not differ significantly between the colonic reconstruction group and the gastric reconstruction group. In terms of heartburn and dumping syndrome, the outcome was markedly better in the colonic reconstruction group (no cases of heartburn or dumping syndrome) than that in the gastric reconstruction group. CONCLUSION: For reconstruction of the esophagus, the colonic interposition and supercharge technique is advantageous and contributes to the patient's quality of life.

• EGF-mediated regulation of IGFBP-3 determines esophageal epithelial cellular response to IGF-I.

  Authors: Munenori Takaoka, Caitlin E Smith, Michael K Mashiba, Takaomi Okawa, Claudia D Andl, Wafik S El-Deiry, Hiroshi Nakagawa

  American journal of physiology. Gastrointestinal and liver physiology. 03/2006; 290(2):G404-16.

  IGF and EGF regulate various physiological and pathological processes. IGF binding protein (IGFBP)-3 regulates cell proliferation in IGF-dependent and -independent fashions. Recently, we identifiedIGF and EGF regulate various physiological and pathological processes. IGF binding protein (IGFBP)-3 regulates cell proliferation in IGF-dependent and -independent fashions. Recently, we identified IGFBP-3 as a novel EGF receptor (EGFR) downstream target molecule in primary and immortalized human esophageal epithelial cells, suggesting an interplay between the EGF and IGF signaling pathways. However, the regulatory mechanisms for IGFBP-3 expression and its functional role in esophageal cell proliferation remain to be elucidated. Herein, we report that IGFBP-3 mRNA and protein were induced upon growth factor deprivation in primary and immortalized human esophageal cells through mechanisms requiring p53-independent de novo mRNA transcription and protein synthesis. This occurred in the face of the activated phosphatidylinositol 3-OH-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. Secreted IGFBP-3 neutralized IGFs and prevented IGF-I receptor (IGF-IR) activation. In contrast, EGF suppressed IGFBP-3 mRNA and protein expression through activation of MAPK in an EGFR-tyrosine kinase-dependent manner to restore the cellular response to IGF-I. When stably overexpressed, wild-type IGFBP-3 but not I56G/L80G/L81G (GGG) mutant IGFBP-3, which has a reduced affinity to IGFs, prevented IGF-I from activating IGF-IR and Akt as well as stimulating cell proliferation. However, unlike other cell types where IGFBP-3 exerts antiproliferative effects, neither wild-type nor GGG mutant IGFBP-3 alone affected cell proliferation or EGFR activity. These results indicate that IGF signaling is subject to negative regulation through IGFBP-3 and positive regulation by EGF, the latter of which suppresses IGFBP-3. This provides a platform for understanding the novel cross talk between EGF- and IGF-mediated pathways.

• COX-2 induction by heparanase in the progression of breast cancer.

  Authors: Takako Imada, Junji Matsuoka, Tetsuji Nobuhisa, Takaomi Okawa, Toshihiro Murata, Yoko Tabuchi, Yasuhiro Shirakawa, Nobuya Ohara, Mehmet Gunduz, Hitoshi Nagatsuka, Tatsuo Umeoka, Yasuhisa Yamamoto, Motowo Nakajima, Noriaki Tanaka, Yoshio Naomoto

  International journal of molecular medicine. 03/2006; 17(2):221-8.

  Breast cancer confined within the lactiferous duct or lobule, without invading the stroma, is called ductal carcinoma in situ (DCIS), whereas breast cancer that has invaded the stroma through theBreast cancer confined within the lactiferous duct or lobule, without invading the stroma, is called ductal carcinoma in situ (DCIS), whereas breast cancer that has invaded the stroma through the basal membrane is called invasive cancer. Heparanase, an endo-beta-D-glucuronidase that specifically degrades heparan sulfate proteoglycans (HSPGs) in the extracellular matrix (ECM), plays an important role when breast cancer cells breach the basal membrane. Recently, we have reported that heparanase is involved in angiogenesis through direct induction of cyclo-oxygenase-2 (COX-2). COX-2 induces vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and is thus involved in neovascularization. The present study was undertaken to analyze surgically resected breast cancer specimens for heparanase and COX-2 expression, using specimens from 59 patients with invasive cancer and 85 patients with DCIS (including 41 cases of DCIS adjacent to invasive cancer). This study yielded the following results: a) the distribution of heparanase within tumor tissue was identical to that of COX-2; b) heparanase expression was more frequent in invasive cancer than in non-invasive cancer; c) a close positive correlation was noted between heparanase and COX-2 expression (this correlation was particularly strong in cases of invasive cancer); and d) COX-2 expression was always seen in cases positive for heparanase expression. Our results indicate that heparanase expression increases during the progression of breast cancer into invasive cancer, and that this change is accompanied by increased COX-2 expression. They also suggest that heparanase may play a novel role for COX-2 mediated tumor angiogenesis in breast-cancer progression.

• Heparanase is involved in angiogenesis in esophageal cancer through induction of cyclooxygenase-2.

  Authors: Takaomi Okawa, Yoshio Naomoto, Tetsuji Nobuhisa, Munenori Takaoka, Takayuki Motoki, Yasuhiro Shirakawa, Tomoki Yamatsuji, Hiroyasu Inoue, Mamoru Ouchida, Mehmet Gunduz, Motowo Nakajima, Noriaki Tanaka

  Clinical cancer research : an official journal of the American Association for Cancer Research. 12/2005; 11(22):7995-8005.

  PURPOSE: Both heparanase and cyclooxygenase-2 (COX-2) are thought to play critical roles for tumor malignancy, including angiogenesis, although it is unknown about their relationship with each otherPURPOSE: Both heparanase and cyclooxygenase-2 (COX-2) are thought to play critical roles for tumor malignancy, including angiogenesis, although it is unknown about their relationship with each other in cancer progression. We hypothesized that they may link to each other on tumor angiogenesis. EXPERIMENTAL DESIGN: The expressions of heparanase and COX-2 in 77 primary human esophageal cancer tissues were assessed by immunohistochemistry to do statistical analysis for the correlation between their clinicopathologic features, microvessel density, and survival of those clinical cases. Human esophageal cancer cells were transduced with heparanase cDNA and used for reverse transcription-PCR and Western blot to determine the expression of heparanase and COX-2. COX-2 promoter vector and its deletion/mutation constructs were also used along with transduction of heparanase cDNA for luciferase assay. RESULTS: Heparanase and COX-2 protein expression exhibited a similar pattern in esophageal tumor tissues, and their expression correlated with tumor malignancy and poor survival. Their expression also revealed a significant correlation with high intratumoral microvessel density. Up-regulation of COX-2 mRNA and protein was observed in esophageal cancer cells transfected with heparanase cDNA. COX-2 promoter was activated after heparanase cDNA was transduced and the deletion/mutation of three transcription factor (cyclic AMP response element, nuclear factor-kappaB, and nuclear factor-interleukin-6) binding elements in COX-2 promoter strongly suppressed its activity. CONCLUSION: Our results suggest that heparanase may play a novel role for COX-2-mediated tumor angiogenesis.

• Effects of imatinib vary with the types of KIT-mutation in gastrointestinal stromal tumor cell lines.

  Authors: Kazuhiro Noma, Yoshio Naomoto, Mehmet Gunduz, Junji Matsuoka, Tomoki Yamatsuji, Yasuhiro Shirakawa, Tetsuji Nobuhisa, Takaomi Okawa, Munenori Takaoka, Yasuko Tomono, Ohmori Hiroyuki, Esra Gunduz, Noriaki Tanaka

  Oncology reports. 10/2005; 14(3):645-50.

  Mutations of proto-oncogene c-kit in gastrointestinal stromal tumors (GISTs) are considered to cause a constitutive activation of KIT responsible for their oncogenesis. Imatinib has therapeuticMutations of proto-oncogene c-kit in gastrointestinal stromal tumors (GISTs) are considered to cause a constitutive activation of KIT responsible for their oncogenesis. Imatinib has therapeutic potential for GISTs because of its inhibitory effect on KIT kinase activity. However, no study has been published concerning the effects of imatinib on GIST cells with various types of KIT mutation. To investigate the effects of imatinib on various c-kit mutations found in GISTs, cell proliferation and apoptosis assays were performed in two GIST cell lines with different KIT mutations. One of the cell lines, GIST-T1, revealed a heterozygous deletion of exon 11 in the c-kit, while the other cell line, GIST882, possessed a homozygous missense mutation of exon 13 in the c-kit gene. Imatinib inhibited proliferation and induced apoptosis in both cell lines. Imatinib potently suppressed proliferation of the GIST882 cell line at the concentration of 1.0 microM, whereas it inhibited the GIST-T1 at 0.1 microM. In two types of activating mutant KIT, imatinib could inhibit the constitutive activation of both types of KIT mutant, although the antiproliferative effect on GIST882 was weaker than on GIST-T1. Western blot analysis revealed that apoptosis related proteins were activated or suppressed by imatinib in both cell lines in the respective manner. Our results suggest that the apoptotic signal trans-duction caused by imatinib in GISTs is susceptible to various types of KIT mutation.

• The role of heparanase in gastrointestinal cancer (Review).

  Authors: Yoshio Naomoto, Munenori Takaoka, Takaomi Okawa, Tetsuji Nobuhisa, Mehmet Gunduz, Noriaki Tanaka

  Oncology reports. 08/2005; 14(1):3-8.

  Heparanase is endoglycosidase that degrades heparan sulfate, the main polysaccharide constituent of the extracellular matrix and basement membrane. Heparanase has been thought to have an importantHeparanase is endoglycosidase that degrades heparan sulfate, the main polysaccharide constituent of the extracellular matrix and basement membrane. Heparanase has been thought to have an important role in the process of cancer invasion and metastasis. Recent studies have revealed that heparanase has multifunctional modulatory effects in the progression of cancer cells and the cell-to-extracellular matrix interaction. Our recent research has shown the important roles of heparanase in the progression of esophagus, stomach and colon cancer, and heparanase expression was closely related to the prognosis of gastrointestinal cancer. Therapies targeting heparanase may result in promising tactics in cancer therapies. Heparanase gene silencing and inhibiton of enzymatic activities have potential use as targets for anticancer drug development. Here, we reviewed the role of heparanase in gastrointestinal tract tumors.

• p53 expression and p21 expression are mutually exclusive in esophageal squamous cell carcinoma.

  Authors: Madoka Hamada, Yoshio Naomoto, Yasuhiro Shirakawa, Tomoki Yamatsuji, Kazuhiro Noma, Takayuki Motoki, Tetsuji Nobuhisa, Takaomi Okawa, Minoru Haisa, Mehmet Gunduz, Junji Matsuoka, Noriaki Tanaka

  Oncology reports. 02/2004; 11(1):57-63.

  The accumulation of p53 protein, which is considered to be caused by a p53 gene mutation, is closely associated with poor prognosis in patients with certain types of carcinomas. The progression ofThe accumulation of p53 protein, which is considered to be caused by a p53 gene mutation, is closely associated with poor prognosis in patients with certain types of carcinomas. The progression of esophageal squamous cell carcinoma (ESCC) is also suspected to depend on p53 gene status. We analyzed the relationship between p53 and p21 protein accumulation in ESCC, and simultaneously analyzed the frequency of apoptosis. Formalin-fixed paraffin-embedded sections were taken from 46 patients who underwent esophagectomy for ESCC. These sections were examined by immunostaining with monoclonal antibodies PAb1801 and EA10 to determine p53 and p21 protein accumulation, respectively. We also analyzed the frequency of apoptosis by TdT-mediated dUTP-biotin nick end-labeling (TUNEL). For estimation of the proportion of stained cells, we used computer analysis with NIH image analysis software. p21 protein accumulation showed an almost inverse distribution to that of p53 protein. In areas where both p53 and p21 proteins were accumulated, few apoptotic cells were observed. Particularly in cases of mucosal tumors, p53 protein was prominently accumulated in the lower layer of the tumor, whereas p21 protein accumulation was confined to the upper layer. Our results suggest that progression of esophageal squamous cell carcinoma is controlled by a p53-dependent pathway.