研究者詳細 - 時野　隆至

論文 - 時野　隆至

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今井崇, 秋野公臣, 豊田実, 鈴木拓, 佐々木泰史, 見田裕章, 井戸川雅史, 鹿島理沙, 荻和弘, 曽我部陽平, 今井浩三, 平塚博義, 時野隆至

日本口腔科学会雑誌 ( (NPO)日本口腔科学会 ) 57 ( 1 ) 160 - 160 2008年01月

Histone Deacetylase Inhibitor FK228 Enhances Adenovirus-mediated p53 Family Gene Therapy in Cancer Models

Yasushi Sasaki, Masashi Idogawa, Hiromu Suzuki, Hiroaki Mita, Minoru Toyota, Yasuhisa Shinomura, Kohzoh Imai, Takashi Tokino

TUMOR BIOLOGY ( KARGER ) 29 ( 4 ) 24 - 24 2008年 [査読有り]

DOI PubMed

In vitro transformation of adult rat hepatic progenitor cells into pancreatic endocrine hormone-producing cells.

Kawasaki H, Mizuguchi T, Kikkawa Y, Oshima H, Sasaki Y, Tokino T, Kokai Y, Miyazaki J, Katsuramaki T, Mitaka T, Hirata K

Journal of hepato-biliary-pancreatic surgery 15 ( 3 ) 310 - 7 2008年 [査読有り] [国内誌]

BACKGROUND/PURPOSE: Pancreatic and duodenal homeobox factor 1 (Pdx-1) plays an important role in initiating differentiation toward pancreatic endocrine cells. The transdifferentiation or transformation of hepatocytes into pancreatic endocrine cells could be feasible, due to their similar cellular origins. Our goal in this study was to see if small hepatocytes (SHs) could give rise to pancreatic endocrine cells via exogenous Pdx-1 gene expression. METHODS: SHs were cultured for 10 days before adenovirus (Adt)-mediated Pdx-1 gene transfection. We performed western blot analysis for pancreatic transcription factors in the nuclei and reverse-transcription polymerase chain reaction (RT-PCR) for the gene expression of pancreatic endocrine hormones. Confocal laser microscanning analysis was used to observe the transformation of SHs. RESULTS: Pancreatic transcription factors such as Pdx-1, Ngn3, NeuroD, Nkx2.2, and Pax6 were induced after Adt-Pdx-1 gene transfection. The mRNA expression of pancreatic endocrine hormones (insulin, glucagon, and somatostatin) was induced after the gene transfection. Pdx-1 was expressed in the nucleus, where the cells were positive for one or more of the hormones and cytokeratin (CK) 8. Some cells were positive for multiple hormones. The insulin level increased while the glucagon level decreased after the glucose loading test, depending on the glucose concentration. CONCLUSIONS: SHs are transformed into functional pancreatic endocrine cells after Pdx-1 gene transfection.

DOI PubMed

Frequent epigenetic inactivation of SFRP genes in hepatocellular carcinoma.

Takagi H, Sasaki S, Suzuki H, Toyota M, Maruyama R, Nojima M, Yamamoto H, Omata M, Tokino T, Imai K, Shinomura Y

Journal of gastroenterology 43 ( 5 ) 378 - 89 2008年 [査読有り] [国内誌]

BACKGROUND: Activation of the Wnt signaling pathway is frequently observed in hepatocellular carcinoma (HCC), though mutation of three of its components, CTNNB1, AXIN1, and AXIN2, is observed substantially less often. METHODS: We examined the relationship between Wnt signaling and epigenetic alteration of secreted frizzled-related protein (SFRP) genes in HCC. RESULTS: We frequently detected the active form of beta-catenin and accumulation of nuclear beta-catenin in liver cancer cell lines. We detected methylation of SFRP family genes in liver cancer cell lines (SFRP1, 9/12, 75%; SFRP2, 7/12, 58%; SFRP4, 3/12, 25%; SFRP5, 7/12, 58%) and primary HCCs (SFRP1, 9/19, 47%; SFRP2, 12/19, 63%; SFRP5, 8/19, 42%), though methylation of SFRP4 was not found in primary HCCs. SFRP methylation also was detected in hepatitis B or C virus-associated chronic hepatitis (SFRP1, 6/37, 16%; SFRP2, 14/37, 38%; SFRP5, 5/37, 14%) and liver cirrhosis (SFRP1, 10/28, 36%; SFRP2, 9/28, 32%; SFRP5, 3/28, 11%), suggesting that methylation of these genes is an early event in liver carcinogenesis. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor (TCF/LEF) transcriptional activity in liver cancer cells, while overexpression of a beta-catenin mutant and depletion of SFRP1 using siRNA synergistically upregulated TCF/LEF transcriptional activity. CONCLUSIONS: Our results confirm the frequent methylation and silencing of Wnt antagonist genes in HCC, and suggest that their loss of function contributes to activation of Wnt signaling during hepatocarcinogenesis.

DOI PubMed

p53 Expression with p21 Suppression by Single Vector Enhances Antitumor Effect

Masashi Idogawa, Yasushi Sasaki, Kohzoh Imai, Yasuhisa Shinomura, Takashi Tokino

TUMOR BIOLOGY ( KARGER ) 29 73 - 73 2008年 [査読有り]

Genomic Mapping of 12p Amplifications in Gastric Cancer Reveal a 0.5-Mb Target Region Including KRAS Locus

Hiroaki Mita, Fumio Aoki, Hirofumi Akashi, Reo Maruyama, Yasushi Sasaki, Hiromu Suzuki, Masashi Idogawa, Lisa Kashima, Minoru Toyota, Kohzoh Imai, Yasuhisa Shinomura, Takashi Tokino

TUMOR BIOLOGY ( KARGER ) 29 83 - 83 2008年 [査読有り]

Frequent epigenetic inactivation of DICKKOPF family genes in human gastrointestinal tumors.

Sato H, Suzuki H, Toyota M, Nojima M, Maruyama R, Sasaki S, Takagi H, Sogabe Y, Sasaki Y, Idogawa M, Sonoda T, Mori M, Imai K, Tokino T, Shinomura Y

Carcinogenesis 28 ( 12 ) 2459 - 66 2007年12月 [査読有り] [国際誌]

Activation of Wnt signaling has been implicated in tumorigenesis, and epigenetic silencing of Wnt antagonist genes has been detected in various cancers. In the present study, we examined the expression and methylation of DICKKOPF (DKK) family genes in gastrointestinal cancer cell lines. We found that all known DKK genes were frequently silenced in colorectal cancer (CRC) cells (DKK1, 3/9, 33%; DKK2, 8/9, 89%; DKK3, 5/9, 56% and DKK4, 5/9, 56%), but not in normal colon mucosa. DKK1, -2 and -3 have 5' CpG islands, and show an inverse relation between expression and methylation. DKK methylation also was frequently observed in gastric cancer (GC) cell lines (DKK1, 6/16, 38%; DKK2, 15/16, 94% and DKK3, 10/16, 63%), but was seen less frequently in hepatocellular carcinoma and pancreatic cancer cell lines. DKKs also were frequently methylated in primary CRCs (DKK1, 7/58, 12%; DKK2, 45/58, 78% and DKK3, 12/58, 21%) and GCs (DKK1, 15/31, 48%; DKK2, 26/31, 84% and DKK3, 12/31, 39%). Against a background of CTNNB1 or APC mutations, Dickkopfs (Dkks) were less effective inhibitors of Wnt signaling than secreted frizzled-related proteins, though over-expression of Dkks suppressed colony formation of CRC cells with such mutations. Our results demonstrate that DKKs are frequent targets of epigenetic silencing in gastrointestinal tumors, and that loss of DKKs may facilitate tumorigenesis through beta-catenin/T-cell factor-independent mechanisms.

DOI PubMed

Gene amplification and overexpression of PRDM14 in breast cancers.

Nishikawa N, Toyota M, Suzuki H, Honma T, Fujikane T, Ohmura T, Nishidate T, Ohe-Toyota M, Maruyama R, Sonoda T, Sasaki Y, Urano T, Imai K, Hirata K, Tokino T

Cancer research 67 ( 20 ) 9649 - 57 2007年10月 [査読有り] [国際誌]

Several genes that encode PR (PRDI-BF1 and RIZ) domain proteins (PRDM) have been linked to human cancers. To explore the role of the PR domain family genes in breast carcinogenesis, we examined the expression profiles of 16 members of the PRDM gene family in a panel of breast cancer cell lines and primary breast cancer specimens using semiquantitative real-time PCR. We found that PRDM14 mRNA is overexpressed in about two thirds of breast cancers; moreover, immunohistochemical analysis showed that expression of PRDM14 protein is also up-regulated. Analysis of the gene copy number revealed that PRDM14 is a target of gene amplification on chromosome 8q13, which is a region where gene amplification has frequently been detected in various human tumors. Introduction of PRDM14 into cancer cells enhanced cell growth and reduced their sensitivity to chemotherapeutic drugs. Conversely, knockdown of PRDM14 by siRNA induced apoptosis in breast cancer cells and increased their sensitivity to chemotherapeutic drugs, suggesting that up-regulated expression of PRDM14 may play an important role in the proliferation of breast cancer cells. That little or no expression of PRDM14 is seen in noncancerous tissues suggests that PRDM14 could be an ideal therapeutic target for the treatment of breast cancer.

DOI PubMed

PRDM5 identified as a target of epigenetic silencing in colorectal and gastric cancer.

Watanabe Y, Toyota M, Kondo Y, Suzuki H, Imai T, Ohe-Toyota M, Maruyama R, Nojima M, Sasaki Y, Sekido Y, Hiratsuka H, Shinomura Y, Imai K, Itoh F, Tokino T

Clinical cancer research : an official journal of the American Association for Cancer Research 13 ( 16 ) 4786 - 94 2007年08月 [査読有り] [国際誌]

PURPOSE: PR (PRDI-BF1 and RIZ) domain proteins (PRDM) are a subfamily of the kruppel-like zinc finger gene products that play key roles during cell differentiation and malignant transformation. The aim of the present study was to begin to examine the involvement of epigenetic alteration of PRDM expression in gastric and colorectal cancer. EXPERIMENTAL DESIGN: We used real-time PCR to assess expression of PRDM1-17. In addition, we used bisulfite PCR to assess DNA methylation and chromatin immunoprecipitation to assess histone modification in colorectal and gastric cancer cell lines lacking PRDM5 expression. RESULTS: Among the 17 PRDM family genes tested, we found that PRDM5 is the most frequently silenced in colorectal and gastric cancer cell lines. Silencing of PRDM5 was mediated by either DNA methylation or trimethylation of Lys(27) of histone H3. Introduction of PRDM5 into cancer cells suppressed cell growth, suggesting that it acts as a tumor suppressor in gastrointestinal cancers. Methylation of PRDM5 was detected in 6.6% (4 of 61) of primary colorectal and 50.0% (39 of 78) of primary gastric cancers but not in noncancerous tissue samples collected from areas adjacent to the tumors. CONCLUSIONS: Our data suggest that epigenetic alteration of PRDM5 (e.g., methylation of its 5'-CpG island or trimethylation of Lys(27) of histone H3) likely plays a key role in the progression of gastrointestinal cancers and may be a useful molecular marker.

DOI PubMed

アデノウイルス介在性p53ファミリー遺伝子療法効果のヒストンデアセチラーゼ阻害剤FK228による増大(The Histone Deacetylase Inhibitor FK228 Increases the Efficacy of Adenovirus-mediated p53 Family Gene Therapy)

佐々木泰史, 根岸秀明, 井戸川雅史, 鈴木拓, 見田裕章, 豊田実, 丸山玲緒, 明石浩史, 篠村恭久, 今井浩三, 時野隆至

日本癌学会総会記事 ( (一社)日本癌学会 ) 66回 129 - 129 2007年08月

口腔癌におけるRAS関連遺伝子の異常について(Alterations of RAS signaling pathway in oral squamous cell carcinoma)

今井崇, 秋野公臣, 豊田実, 鈴木拓, 佐々木泰史, 見田裕章, 井戸川雅史, 鹿島理沙, 曽我部陽平, 渡邊嘉行, 今井浩三, 平塚博義, 時野隆至

日本癌学会総会記事 ( (一社)日本癌学会 ) 66回 314 - 314 2007年08月

デジタルゲノムスキャンにより同定された胃癌におけるK-rasゲノム増幅(Genomic amplification of K-ras in gastric cancer identified by digital genome scanning)

見田裕章, 豊田実, 青木文夫, 明石浩史, 丸山玲緒, 佐々木泰史, 鈴木拓, 井戸川雅史, 鹿島理沙, 今井浩三, 篠村恭久, 時野隆至

日本癌学会総会記事 ( (一社)日本癌学会 ) 66回 231 - 231 2007年08月

CHFR有糸分裂チェックポイントタンパク質はNFκBの転写活性を抑制する(CHFR mitotic checkpoint protein inhibits the transcriptional activity of NF-κB)

鹿島理沙, 見田裕章, 豊田実, 佐々木泰史, 鈴木拓, 井戸川雅史, 時野隆至

日本癌学会総会記事 ( (一社)日本癌学会 ) 66回 482 - 482 2007年08月

多発性骨髄腫においてDNAメチル化により不活化される遺伝子の網羅的解析(Genomic Screening for Genes Silenced by DNA Methylation in Multiple Myeloma)

丸山玲緒, 豊田実, 鈴木拓, 安井寛, 林敏昭, 酒井基, 石田禎夫, 今井浩三, 時野隆至, 篠村恭久

日本癌学会総会記事 ( (一社)日本癌学会 ) 66回 458 - 458 2007年08月

Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer

M. Nojima, H. Suzuki, M. Toyota, Y. Watanabe, R. Maruyama, S. Sasaki, Y. Sasaki, H. Mita, N. Nishikawa, K. Yamaguchi, K. Hirata, F. Itoh, T. Tokino, M. Mori, K. Imai, Y. Shinomura

ONCOGENE ( NATURE PUBLISHING GROUP ) 26 ( 32 ) 4699 - 4713 2007年07月 [査読有り]

Activation of Wnt signaling has been implicated in gastric tumorigenesis, although mutations in APC (adenomatous polyposis coli), CTNNB1 (beta-catenin) and AXIN are seen much less frequently in gastric cancer (GC) than in colorectal cancer. In the present study, we investigated the relationship between activation of Wnt signaling and changes in the expression of secreted frizzled-related protein (SFRP) family genes in GC. We frequently observed nuclear beta-catenin accumulation (13/15; 87%) and detected the active form of beta-catenin in most (12/16; 75%) GC cell lines. CpG methylation-dependent silencing of SFRP1, SFRP2 and SFRP5 was frequently seen among GC cell lines (SFRP1, 16/16, 100%; SFRP2, 16/16, 100%; SFRP5, 13/16, 81%) and primary GC specimens (SFRP1, 42/46, 91%; SFRP2, 44/46, 96%; SFRP5, 30/46, 65%),and treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine rapidly restored SFRP expression. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor transcriptional activity, suppressed cell growth and induced apoptosis in GC cells. Analysis of global expression revealed that overexpression of SFRP2 repressed Wnt target genes and induced changes in the expression of numerous genes related to proliferation, growth and apoptosis in GC cells. It thus appears that aberrant SFRP methylation is one of the major mechanisms by which Wnt signaling is activated in GC.

DOI

Antitumor effect of adenovirus-mediated p53 family gene transfer on osteosarcoma cell lines.

Oshima Y, Sasaki Y, Negishi H, Idogawa M, Toyota M, Yamashita T, Wada T, Nagoya S, Kawaguchi S, Yamashita T, Tokino T

Cancer biology & therapy 6 ( 7 ) 1058 - 66 2007年07月 [査読有り] [国際誌]

Osteosarcoma (OS) is one of the most common malignancies of the bone. Although prognosis of OS has improved significantly during the past several years due to more intensive chemotherapy and radiotherapy regimens, new therapeutic approaches are needed for recurrent and inoperable cases, p73 and p63, like their homologue, the tumor suppressor p53, are able to induce apoptosis in several cell types. Here, we evaluated the antitumor effects of p73 and p63 on eleven different human OS cell lines. In vitro, adenovirus-mediated transduction of p63gamma induced apoptosis in OS cells that are resistant to p53-mediated apoptosis, while less effect was observed following transduction of p73alpha or p63alpha. Interestingly, the apoptotic effects of p63gamma were greater than those of wild-type p53 in OS cells carrying MDM2-amplification. We then determined the in vivo therapeutic effect of intratumoral injection of adenovirus-vector expressing p53 family members on xenografts derived from Saos-2 cells implanted in nude mice, and showed that infection with p63y significantly suppressed tumor growth compared with p53. In addition, exogenous p73beta and p63gamma significantly increased the chemosensitivity of OS cells to doxorubicin and cisplatin, chemotherapeutic agents commonly used in the treatment of OS. Our results suggest that adenovirus-mediated transduction of p53 family members may have utility in gene therapy for OS, particularly in combination with chemotherapeutic agents.

PubMed

Ku70 and poly(ADP-ribose) polymerase-1 competitively regulate beta-catenin and T-cell factor-4-mediated gene transactivation: possible linkage of DNA damage recognition and Wnt signaling.

Idogawa M, Masutani M, Shitashige M, Honda K, Tokino T, Shinomura Y, Imai K, Hirohashi S, Yamada T

Cancer research 67 ( 3 ) 911 - 8 2007年02月 [査読有り] [国際誌]

Formation of the T-cell factor-4 (TCF-4) and beta-catenin nuclear complex is considered crucial to embryonic development and colorectal carcinogenesis. We previously reported that poly(ADP-ribose) polymerase-1 (PARP-1) interacts with the TCF-4 and beta-catenin complex and enhances its transcriptional activity. However, its biological significance remains unexplained. Using immunoprecipitation and mass spectrometry, we found that two Ku proteins, Ku70 and Ku80, were also associated with the complex. Knockdown of Ku70 by RNA interference increased the amount of beta-catenin associated with TCF-4 and enhanced the transcriptional activity. PARP-1 competed with Ku70 for binding to TCF-4. Treatment with bleomycin, a DNA-damaging alkylating agent, induced polyADP-ribosylation of PARP-1 protein and inhibited its interaction with TCF-4. Bleomycin conversely increased the amounts of Ku70 coimmunoprecipitated with TCF-4 and removed beta-catenin from TCF-4. We propose a working model in which the transcriptional activity of TCF-4 is regulated by the relative amount of Ku70, PARP-1, and beta-catenin proteins binding to TCF-4. Identification of the functional interaction of Ku70 as well as PARP-1 with the TCF-4 and beta-catenin transcriptional complex may provide insights into a novel linkage between DNA damage recognition/repair and Wnt signaling.

DOI PubMed

Identification of DFNA5 as a target of epigenetic inactivation in gastric cancer.

Akino K, Toyota M, Suzuki H, Imai T, Maruyama R, Kusano M, Nishikawa N, Watanabe Y, Sasaki Y, Abe T, Yamamoto E, Tarasawa I, Sonoda T, Mori M, Imai K, Shinomura Y, Tokino T

Cancer science 98 ( 1 ) 88 - 95 2007年01月 [査読有り] [国際誌]

Epigenetic gene inactivation plays a key role in the development of various types of cancer. Using methylated CpG island amplification coupled with representational difference analysis to identify genes inactivated by DNA methylation in gastric cancer, we identified seven DNA fragments corresponding to the 5' CpG islands of the affected genes. One of the clones recovered was identical to the 5' flanking region of DFNA5, a gene previously shown to be associated with deafness and induced by DNA damage. Further analysis revealed that DFNA5 is expressed in normal tissues but is down-regulated in gastric cancer cell lines due to methylation of the region around its transcription start site. Treating gastric cancer cells that lacked DFNA5 expression with a methyltransferase inhibitor, 5-aza-2'-deoxycytidine, restored the gene's expression. Methylation of DFNA5 was detected in 50% of primary gastric tumors, and was correlated with positivity for Epstein-Barr virus and the absence of metastasis. Moreover, introduction of exogenous DFNA5 into silenced cells suppressed colony formation. Taken together, these data suggest that the silencing of DFNA5 occurs frequently in gastric cancer and may play a key role in development and progression of the disease.

DOI PubMed

Genomic screening for genes silenced by DNA methylation in multiple myeloma

Yasui, Hiroshi, Toyota, Minoru, Maruyama, Reo, Tarasawa, Isao, Suzuki, Hiromu, Hayashi, Toshiaki, Sakai, Hajime, Ishida, Tadao, Asaoku, Hideki, Tokino, Takashi, Imai, Kohzoh, Shinomura, Yasuhisa

TUMOR BIOLOGY ( KARGER ) 28 78 - 78 2007年 [査読有り]

Proteins interacting with CHFR, mitotic-checkpoint ubiquitin ligase

Mita H, Toyota M, Sasaki Y, Suzuki H, Idogawa M, Kashima L, Tokino T

Tumor Research ( Sapporo Medical University ) 41 23 - 41 2006年12月 [査読有り]

Cell cycle progression is monitored by checkpoint mechanisms to ensure the integrity of the genome. CHFR which contains a RING domain and has ubiquitin ligase activity, a novel mitotic checkpoint gene, delays chromosome condensation in cells treated with microtubule poisons. CHFR is inactivated by promoter methylation and point mutations in various human tumors, and cancer cells lacking CHFR are sensitive to microtubule inhibitors. However, few reports are available on the molecular mechanism that accounts for the link between the sensitivity of cancer cells to microtubule inhibitors and the physiological function of CHFR. In the present study, we isolated cellular proteins capable of interacting with CHFR using yeast two-hybrid method to clarify the function of CHFR. As a result of the screening, we isolated canonical and noncanonical E2 ubiquitin conjugating enzymes as CHFR interacting proteins, which are involved in proteolytic and non-proteolytic ubiquitination respectively. This raises the possibility that CHFR is switching canonical and non-canonical ubiquitination depending on the situation of cells. On the other hand, we isolated gadd34 which interacted with the FHA domain of CHFR by two-hybrid screen. Coexpression in mammalian cells showed that gadd34 interacted with the FHA domain of CHFR, but gadd34 is not the substrate for CHFR, rather it promoted autoubiquitination of CHFR. Furthermore, CHFR moved, in part, from nucleus to cytoplasm in the presence of microtubule inhibitor docetaxel, which enabled colocalization of CHFR and gadd34 in cytoplasm. This colocalization was followed by cell death. These findings suggest that gadd34 and CHFR cooperate to mediate cell death in response to mitotic stress.

DOI CiNii

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