Details of a Researcher - SASAKI Yasushi

Papers - SASAKI Yasushi

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CHFR protein regulates mitotic checkpoint by targeting PARP-1 protein for ubiquitination and degradation.

Kashima L, Idogawa M, Mita H, Shitashige M, Yamada T, Ogi K, Suzuki H, Toyota M, Ariga H, Sasaki Y, Tokino T

The Journal of biological chemistry 287 ( 16 ) 12975 - 84 2012.02 [Refereed] [International journal]

The mitotic checkpoint gene CHFR (checkpoint with forkhead-associated (FHA) and RING finger domains) is silenced by promoter hypermethylation or mutated in various human cancers, suggesting that CHFR is an important tumor suppressor. Recent studies have reported that CHFR functions as an E3 ubiquitin ligase, resulting in the degradation of target proteins. To better understand how CHFR suppresses cell cycle progression and tumorigenesis, we sought to identify CHFR-interacting proteins using affinity purification combined with mass spectrometry. Here we show poly(ADP-ribose) polymerase 1 (PARP-1) to be a novel CHFR-interacting protein. In CHFR-expressing cells, mitotic stress induced the autoPARylation of PARP-1, resulting in an enhanced interaction between CHFR and PARP-1 and an increase in the polyubiquitination/degradation of PARP-1. The decrease in PARP-1 protein levels promoted cell cycle arrest at prophase, supporting that the cells expressing CHFR were resistant to microtubule inhibitors. In contrast, in CHFR-silenced cells, polyubiquitination was not induced in response to mitotic stress. Thus, PARP-1 protein levels did not decrease, and cells progressed into mitosis under mitotic stress, suggesting that CHFR-silenced cancer cells were sensitized to microtubule inhibitors. Furthermore, we found that cells from Chfr knockout mice and CHFR-silenced primary gastric cancer tissues expressed higher levels of PARP-1 protein, strongly supporting our data that the interaction between CHFR and PARP-1 plays an important role in cell cycle regulation and cancer therapeutic strategies. On the basis of our studies, we demonstrate a significant advantage for use of combinational chemotherapy with PARP inhibitors for cancer cells resistant to microtubule inhibitors.

p53 negatively regulates the hepatoma growth factor HDGF.

Sasaki Y, Negishi H, Idogawa M, Yokota I, Koyama R, Kusano M, Suzuki H, Fujita M, Maruyama R, Toyota M, Saito T, Tokino T

Cancer research 71 ( 22 ) 7038 - 47 2011.10 [Refereed] [International journal]

Authorship： Lead author

Hepatoma-derived growth factor (HDGF) is a secreted heparin-binding growth factor that has been implicated in cancer development and progression. Here, we report that HDGF is a critical target for transcriptional repression by the tumor suppressor p53. Endogenous HDGF expression was decreased in cancer cells with introduction of wild-type p53, which also downregulated HDGF expression after DNA damage. In support of the likelihood that HDGF is a critical driver of cancer cell growth, addition of neutralizing HDGF antibodies to culture media was sufficient to block cell growth, migration, and invasion. Similarly, these effects were elicited by conditioned culture medium from p53-expressing cells, and they could be reversed by the addition of recombinant human HDGF. Interestingly, we found that HDGF was overexpressed also in primary gastric, breast, and lung cancer tissues harboring mutant p53 genes. Mechanistic investigations revealed that p53 repressed HDGF transcription by altering HDAC-dependent chromatin remodeling. Taken together, our results reveal a new pathway in which loss of p53 function contributes to the aggressive pathobiological potential of human cancers by elevating HDGF expression.

Genome-wide profiling of chromatin signatures reveals epigenetic regulation of MicroRNA genes in colorectal cancer.

Suzuki H, Takatsuka S, Akashi H, Yamamoto E, Nojima M, Maruyama R, Kai M, Yamano HO, Sasaki Y, Tokino T, Shinomura Y, Imai K, Toyota M

Cancer research 71 ( 17 ) 5646 - 58 2011.07 [Refereed] [International journal]

Altered expression of microRNAs (miRNA) occurs commonly in human cancer, but the mechanisms are generally poorly understood. In this study, we examined the contribution of epigenetic mechanisms to miRNA dysregulation in colorectal cancer by carrying out high-resolution ChIP-seq. Specifically, we conducted genome-wide profiling of trimethylated histone H3 lysine 4 (H3K4me3), trimethylated histone H3 lysine 27 (H3K27me3), and dimethylated histone H3 lysine 79 (H3K79me2) in colorectal cancer cell lines. Combining miRNA expression profiles with chromatin signatures enabled us to predict the active promoters of 233 miRNAs encoded in 174 putative primary transcription units. By then comparing miRNA expression and histone modification before and after DNA demethylation, we identified 47 miRNAs encoded in 37 primary transcription units as potential targets of epigenetic silencing. The promoters of 22 transcription units were associated with CpG islands (CGI), all of which were hypermethylated in colorectal cancer cells. DNA demethylation led to increased H3K4me3 marking at silenced miRNA genes, whereas no restoration of H3K79me2 was detected in CGI-methylated miRNA genes. DNA demethylation also led to upregulation of H3K4me3 and H3K27me3 in a number of CGI-methylated miRNA genes. Among the miRNAs we found to be dysregulated, many of which are implicated in human cancer, miR-1-1 was methylated frequently in early and advanced colorectal cancer in which it may act as a tumor suppressor. Our findings offer insight into the association between chromatin signatures and miRNA dysregulation in cancer, and they also suggest that miRNA reexpression may contribute to the effects of epigenetic therapy.

Epigenetic alteration of DNA in mucosal wash fluid predicts invasiveness of colorectal tumors.

Kamimae S, Yamamoto E, Yamano HO, Nojima M, Suzuki H, Ashida M, Hatahira T, Sato A, Kimura T, Yoshikawa K, Harada T, Hayashi S, Takamaru H, Toyota M

Cancer prevention research (Philadelphia, Pa.) 4 ( 5 ) 674 - 83 2011.05 [Refereed] [International journal]

Although conventional colonoscopy is considered the gold standard for detecting colorectal tumors, accurate staging is often difficult because advanced histology may be present in small colorectal lesions. We collected DNA present in mucosal wash fluid from patients undergoing colonoscopy and then assessed the methylation levels of four genes frequently methylated in colorectal cancers to detect invasive tumors. We found that methylation levels in wash fluid were significantly higher in patients with invasive than those with noninvasive tumors. Cytologic and K-ras mutation analyses suggested that mucosal wash fluid from invasive tumors contained greater numbers of tumor cells than wash fluid from noninvasive tumors. Among the four genes, levels of mir-34b/c methylation had the greatest correlation with the invasion and showed the largest area under the receiver operating characteristic curve (AUC = 0.796). Using cutoff points of mir-34b/c methylation determined by efficiency considerations, the sensitivity/specificity were 0.861/0.657 for the 13.0% (high sensitivity) and 0.765/0.833 for the 17.8% (well-balanced) cutoffs. In the validation test set, the AUC was also very high (0.915), the sensitivity/specificity were 0.870/0.875 for 13.0% and 0.565/0.958 for 17.8%. Using the diagnostic tree constructed by an objective algorithm, the diagnostic accuracy of the invasiveness of colorectal cancer was 91.3% for the training set and 85.1% for the test set. Our results suggest that analysis of the methylation of DNA in mucosal wash fluid may be a good molecular marker for predicting the invasiveness of colorectal tumors.

Identification and characterization of early growth response 2, a zinc-finger transcription factor, as a p53-regulated proapoptotic gene

Ikuko Yokota, Yasushi Sasaki, Lisa Kashima, Masashi Idogawa, Takashi Tokino

International Journal of Oncology 37 ( 6 ) 1407 - 1416 2010.12 [Refereed] [International journal]

Authorship： Corresponding author

Tumor suppressor p53 is a transcription factor that induces growth arrest and/or apoptosis in response to cellular stress. In recent years, many genes have been identified as p53-regulated genes; however, no single target gene has been shown to be required for the apoptotic effect. Using microarray analysis, we have identified the transcription factor early growth response 2 (EGR2) as a target of the p53 family, specifically p53, p63 and p73. EGR2 expression was up-regulated by DNA damage-induced p53 activity, as well as by overexpression of p53 family genes. Furthermore, we identified a responsive element to p53, TAp63, and TAp73 within the EGR2 gene. This response element is highly conserved between human and rodents. We also found that overexpression of EGR2 induced apoptosis when combined with anticancer agents. Conversely, inactivation of EGR2 attenuated p53-mediated apoptosis. The results presented here suggest that EGR2 is a direct transcriptional target of p53 family that can in part mediate the p53-dependent apoptotic pathway.

p53 family network and human cancer

Sasaki Y, Idogawa M, Yokota I, Kashima L, Tokino T

Tumor Research 45 33 - 44 2010.12 [Refereed]

Myogenic lineage differentiated mesenchymal stem cells enhance recovery from dextran sulfate sodium-induced colitis in the rat.

Hiroki Tanaka, Yoshiaki Arimura, Takashi Yabana, Akira Goto, Masayo Hosokawa, Kanna Nagaishi, Kentaro Yamashita, Hiroyuki Yamamoto, Yasushi Sasaki, Mineko Fujimiya, Kohzoh Imai, Yasuhisa Shinomura

Journal of gastroenterology 46 ( 2 ) 143 - 52 2010.09 [Refereed] [Domestic journal]

Although mounting evidence implicates mesenchymal stem cells (MSCs) in intestinal tissue repair, uncertainty remains concerning the distribution, function, and fate of repopulating MSCs in recipient colonic tissues. Therefore, we investigated the role of transplanted MSCs in the repair phase of DSS colitis.LacZ-labeled rat MSCs were transplanted into rats with colitis induced by 4% DSS on day 2. Regular water replaced the DSS solution on day 6. Therapeutic effect was evaluated on day 9 by clinicopathologic and growth factor/cytokine expression profiles. We analyzed the Notch signaling pathway by Western blotting and characterized immunofluorescence of lacZ-labeled MSCs with confocal laser microscopy. In vivo differentiation of MSC was confirmed by transmission electron microscopy (TEM).Recovery of colitis was modestly but significantly promoted by MSC transplantation due to proceeding cell cycle and inhibiting apoptosis in the epithelia. Tgfa mRNA expression increased significantly, while Notch signaling was inhibited in the colonic tissues with MSC transplantation. β-Galactosidase-positive cells, which expressed α-SMA, desmin, and vimentin, were infrequently detected in the lamina propria stroma. DSS exposure in vitro proved to be the most potent inducer for α-SMA in MSCs where TEM demonstrated myogenic lineage differentiation.We found that MSCs transplantation modestly promoted the repair of DSS colitis. The donor-derived MSCs were likely reprogrammed to differentiate to myogenic lineage cells by cues from the micro milieu. Further characterization of these cells is warranted as a basis for applying cell-based therapy for inflammatory bowel disease.

DNA methylation of interferon regulatory factors in gastric cancer and noncancerous gastric mucosae.

Yamashita M, Toyota M, Suzuki H, Nojima M, Yamamoto E, Kamimae S, Watanabe Y, Kai M, Akashi H, Maruyama R, Sasaki Y, Yamano H, Sugai T, Shinomura Y, Itoh F

Cancer Science 101 ( 7 ) 1708 - 16 2010.04 [Refereed] [International journal]

Interferon regulatory factors (IRFs) are transcription factors known to play key roles in innate and adaptive immune responses, cell growth, apoptosis, and development. Their function in tumorigenesis of gastric cancer remains to be determined, however. In the present study, therefore, we examined epigenetic inactivation of IRF1-9 in a panel of gastric cancer cell lines. We found that expression of IRF4, IRF5, and IRF8 was frequently suppressed in gastric cancer cell lines; that methylation of the three genes correlated with their silencing; and that treating the cells with the demethylating agent 5-aza-2'-deoxycytidine (DAC) restored their expression. Expression of IRF5 in cancer cells was enhanced by the combination of DAC treatment and adenoviral vector-mediated expression of p53, p63, or p73. Interferon-gamma-induced expression of IRF8 was also enhanced by DAC. Moreover, treating gastric cancer cells with DAC enhanced the suppressive effects of interferon-alpha, interferon-beta, and interferon-gamma on cell growth. Among a cohort of 455 gastric cancer and noncancerous gastric tissue samples, methylation of IRF4 was frequently observed in both gastric cancer specimens and noncancerous specimens of gastric mucosa from patients with multiple gastric cancers, which suggests IRF4 methylation could be a useful molecular marker for diagnosing recurrence of gastric cancers. Our findings indicate that epigenetic IRF inactivation plays a key role in tumorigenesis of gastric cancer, and that inhibition of DNA methylation may restore the antitumor activity of interferons through up-regulation of IRFs.

幽門狭窄を来した進行胃癌に対して経皮内視鏡的胃瘻造設術（PEG）の腸瘻化（PEG-J）が奏効した１例

山下真幸, 足立靖, 田中浩紀, 安達靖代, 明石浩史, 佐々木泰史, 加藤康夫, 伊東文生, 篠村恭久, 遠藤高夫

日本消化器内視鏡学会雑誌 ( (一社)日本消化器内視鏡学会 ) 52 ( 5 ) 1415 - 1420 2010 [Refereed]

幽門狭窄をきたした切除不能進行胃癌の90歳代男性症例について検討した。減圧と栄養・投薬を目的に小腸留置型ダブルルーメンチューブを用いた経皮内視鏡的胃瘻造設術(PEG)の腸瘻化(PEG-J)を二期的に行った。胃瘻造設から7日目に経胃瘻的内視鏡(TGE)を用いてチューブを十二指腸水平脚へ誘導した。TGEは軽い抵抗はあったものの、容易に狭窄部を通過でき、有用であった。術後、経鼻胃管留置および中心静脈栄養を中止することができ、退院可能となった。PEG-Jは、幽門狭窄胃癌に対する緩和医療として、選択しうる治療法であると思われた。

Genomic screening for genes upregulated by demethylation revealed novel targets of epigenetic silencing in breast cancer.

Fujikane T, Nishikawa N, Toyota M, Suzuki H, Nojima M, Maruyama R, Ashida M, Ohe-Toyota M, Kai M, Nishidate T, Sasaki Y, Ohmura T, Hirata K, Tokino T

Breast cancer research and treatment 122 ( 3 ) 699 - 710 2009.10 [Refereed] [International journal]

Breast cancer arises through the accumulation of multiple genetic alterations and epigenetic changes such as methylation, which silences gene expression in a variety of cancers. In the present study, we applied genomic screening to identify genes upregulated by the demethylating agent 5-aza-2'-deoxycytidine (DAC) in a human breast cancer cell line (MCF7). We identified 288 genes upregulated and 29 genes downregulated more than fivefold after treatment with DAC, and gene ontology analyses revealed the genes to be involved in immune responses, apoptosis, and cell differentiation. In addition, real-time PCR analysis of ten genes silenced in MCF7 cells confirmed that they are upregulated by DAC, while bisulfite-pyrosequencing analysis confirmed that nine of those genes were silenced by methylation. We also found that treating MCF7 cells with DAC restored induction of DFNA5 by p53, as well as by two other p53 family genes, p63gamma and p73beta. Introduction of NTN4 into MCF7 cells suppressed cell growth, indicating that NTN4 has tumor suppressive activity. In primary breast cancers, we detected cancer-specific methylation of NTN4, PGP9.5, and DKK3, suggesting that methylation of these genes could be useful markers for diagnosis of breast cancer. Thus, DNA methylation appears to be a common event in breast cancer, and the genes silenced by methylation could be useful targets for both diagnosis and therapy.

Enhancing epithelial engraftment of rat mesenchymal stem cells restores epithelial barrier integrity.

Takashi Yabana, Yoshiaki Arimura, Hiroki Tanaka, Akira Goto, Masayo Hosokawa, Kanna Nagaishi, Kentaro Yamashita, Hiroyuki Yamamoto, Yasushi Adachi, Yasushi Sasaki, Masaharu Isobe, Mineko Fujimiya, Kohzoh Imai, Yasuhisa Shinomura

The Journal of pathology 218 ( 3 ) 350 - 9 2009.07 [Refereed] [International journal]

The cellular origin, in vivo function and fate of donor bone marrow-derived cells residing in the recipient intestinal epithelial cells, pericryptal myofibroblasts or endothelial cells remain obscure. Although 'immunoprivileged' mesenchymal stem cells (MSCs) are prime candidates for cell- and gene-based therapy, their precise role in colitis remains largely undetermined. Using a dextran sulphate sodium (DSS) colitis with busulphan (BU)-induced hypoplastic marrow model, we examined the therapeutic effects of MSC transplantation, focusing on the role of MSCs as both cell providers and immunomodulators. Donor-derived MSCs were detected by eGFP immunofluorescence and fluorescence in situ hybridization for Y-chromosome (Y-FISH) analysis. Western blot analysis of apical-most tight junction proteins was performed with antibodies against claudin-2, -7, -8, -12, -13, -15 and ZO-1. Cytokine and cell cycle profiles were analysed by semi-quantitative RT-PCR and flow cytometry. Susceptibility to DSS colitis was significantly increased by co-existing BU-induced bone marrow hypoplasia and this increase was significantly reduced by enhancing epithelial engraftment of MSCs, an effect depending on restoring epithelial barrier integrity rather than inhibiting host immune responses. We provide evidence that implicates MSCs in maintaining epithelial barrier function by reassembling apical-most tight junction proteins, claudins. The therapeutic efficacy of extrinsic MSCs depends on enhancing epithelial engraftment in damaged crypts by busulphan conditioning. Such a role for the MSC-derived intestinal cells in colitis therapy merits further examination and may offer a promising new treatment for inflammatory bowel disease (IBD).

IGFBP7 is a p53-responsive gene specifically silenced in colorectal cancer with CpG island methylator phenotype.

Suzuki H, Igarashi S, Nojima M, Maruyama R, Yamamoto E, Kai M, Akashi H, Watanabe Y, Yamamoto H, Sasaki Y, Itoh F, Imai K, Sugai T, Shen L, Issa JP, Toyota M

Carcinogenesis 31 ( 3 ) 342 - 9 2009.07 [Refereed] [International journal]

A subset of colorectal cancers (CRCs) show simultaneous methylation of multiple genes; these tumors have the CpG island methylator phenotype (CIMP). CRCs with CIMP show a specific pattern of genetic alterations, including a high frequency of BRAF mutations and a low frequency of p53 mutations. We therefore hypothesized that genes inactivated by DNA methylation are involved in the BRAF- and p53-signaling pathways. Among those, we examined the epigenetic inactivation of insulin-like growth factor-binding protein 7 (IGFBP7) expression in CRCs. We found that in CRC cell lines, the silencing of IGFBP7 expression was correlated with high levels of DNA methylation and low levels of histone H3K4 methylation. Luciferase and chromatin immunoprecipitation assays in unmethylated cells revealed that p53 induces expression of IGFBP7 upon binding to a p53 response element within intron 1 of the gene. Treating methylated CRC cell lines with 5-aza-2'-deoxycytidine restored p53-induced IGFBP7 expression. Levels of IGFBP7 methylation were also significantly higher in primary CRC specimens than in normal colonic tissue (P < 0.001). Methylation of IGFBP7 was correlated with BRAF mutations, an absence of p53 mutations and the presence of CIMP. Thus, epigenetic inactivation of IGFBP7 appears to play a key role in tumorigenesis of CRCs with CIMP by enabling escape from p53-induced senescence.

A novel method, digital genome scanning detects KRAS gene amplification in gastric cancers: Involvement of overexpressed wild-type KRAS in downstream signaling and cancer cell growth

Hiroaki Mita, Minoru Toyota, Fumio Aoki, Hirofumi Akashi, Reo Maruyama, Yasushi Sasaki, Hiromu Suzuki, Masashi Idogawa, Lisa Kashima, Kazuyoshi Yanagihara, Masahiro Fujita, Masao Hosokawa, Masanobu Kusano, Sorin Vasile Sabau, Haruyuki Tatsumi, Kohzoh Imai, Yasuhisa Shinomura, Takashi Tokino

BMC Cancer 9 198 - 198 2009.06 [Refereed] [International journal]

Background: Gastric cancer is the third most common malignancy affecting the general population worldwide. Aberrant activation of KRAS is a key factor in the development of many types of tumor, however, oncogenic mutations of KRAS are infrequent in gastric cancer. We have developed a novel quantitative method of analysis of DNA copy number, termed digital genome scanning (DGS), which is based on the enumeration of short restriction fragments, and does not involve PCR or hybridization. In the current study, we used DGS to survey copy-number alterations in gastric cancer cells. Methods: DGS of gastric cancer cell lines was performed using the sequences of 5000 to 15000 restriction fragments. We screened 20 gastric cancer cell lines and 86 primary gastric tumors for KRAS amplification by quantitative PCR, and investigated KRAS amplification at the DNA, mRNA and protein levels by mutational analysis, real-time PCR, immunoblot analysis, GTP-RAS pull-down assay and immunohistochemical analysis. The effect of KRAS knock-down on the activation of p44/42 MAP kinase and AKT and on cell growth were examined by immunoblot and colorimetric assay, respectively. Results: DGS analysis of the HSC45 gastric cancer cell line revealed the amplification of a 500-kb region on chromosome 12p12.1, which contains the KRAS gene locus. Amplification of the KRAS locus was detected in 15% (3/20) of gastric cancer cell lines (8-18-fold amplification) and 4.7% (4/86) of primary gastric tumors (8-50-fold amplification). KRAS mutations were identified in two of the three cell lines in which KRAS was amplified, but were not detected in any of the primary tumors. Overexpression of KRAS protein correlated directly with increased KRAS copy number. The level of GTP-bound KRAS was elevated following serum stimulation in cells with amplified wild-type KRAS, but not in cells with amplified mutant KRAS. Knock-down of KRAS in gastric cancer cells that carried amplified wild-type KRAS resulted in the inhibition of cell growth and suppression of p44/42 MAP kinase and AKT activity. Conclusion: Our study highlights the utility of DGS for identification of copy-number alterations. Using DGS, we identified KRAS as a gene that is amplified in human gastric cancer. We demonstrated that gene amplification likely forms the molecular basis of overactivation of KRAS in gastric cancer. Additional studies using a larger cohort of gastric cancer specimens are required to determine the diagnostic and therapeutic implications of KRAS amplification and overexpression. © 2009 Mita et al; licensee BioMed Central Ltd.

Genomic screening for genes silenced by DNA methylation revealed an association between RASD1 inactivation and dexamethasone resistance in multiple myeloma.

Nojima M, Maruyama R, Yasui H, Suzuki H, Maruyama Y, Tarasawa I, Sasaki Y, Asaoku H, Sakai H, Hayashi T, Mori M, Imai K, Tokino T, Ishida T, Toyota M, Shinomura Y

Clinical cancer research : an official journal of the American Association for Cancer Research 15 ( 13 ) 4356 - 64 2009.06 [Refereed] [International journal]

PURPOSE: Epigenetic changes such as DNA methylation play a key role in the development and progression of multiple myeloma. Our aim in the present study was to use genomic screening to identify genes targeted for epigenetic inactivation in multiple myeloma and assess their role in the development of resistance to dexamethasone. EXPERIMENTAL DESIGN: Gene expression was examined using microarray screening, reverse transcription-PCR, and real-time quantitative PCR. DNA methylation was examined using bisulfite PCR, bisulfite sequencing, and bisulfite pyrosequencing in 14 multiple myeloma cell lines, 87 multiple myeloma specimens, and 12 control bone marrow samples. WST-8 assays were used to assess cell viability after treatment with 5-aza-2'-deoxycytidine and/or dexamethasone. RESULTS: Microarray analysis was done to screen for genes up-regulated by 5-aza-2'-deoxycytidine. In RPMI8226 cells, 128 genes were up-regulated, whereas 83 genes were up-regulated in KMS12PE cells. Methylation of 22 genes with CpG islands in their 5' regions, including RASD1, was confirmed. Methylation of RASD1 was associated with its inactivation, which correlated with resistance to dexamethasone. Treating multiple myeloma cells with 5-aza-2'-deoxycytidine restored sensitivity to dexamethasone. Methylation of RASD1 was also detected in a subset of primary multiple myeloma specimens, and the levels of methylation were increased after repeated antitumor treatments. Gene signature analysis revealed various genes to be synergistically induced by treatment with a combination of 5-aza-2'-deoxycytidine plus dexamethasone. CONCLUSION: Our findings indicate that epigenetic inactivation of genes, including RASD1, plays a key role in the development of dexamethasone resistance in multiple myeloma. Moreover, they show the utility of demethylation therapy in cases of advanced multiple myeloma.

miRNAによるp21発現誘導抑制能を付加したp53発現ベクターによる癌治療効果の増強

井戸川雅史, 佐々木泰史, 篠村恭久, 今井浩三, 時野隆至

Drug Delivery System ( 日本DDS学会 ) 24 ( 3 ) 332 - 332 2009.06

CHFR, a potential tumor suppressor, downregulates interleukin-8 through the inhibition of NF-kappaB.

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

Oncogene 2009.05 [Refereed]

A single recombinant adenovirus expressing p53 and p21-targeting artificial microRNAs efficiently induces apoptosis in human cancer cells.

Idogawa M, Sasaki Y, Suzuki H, Mita H, Imai K, Shinomura Y, Tokino T

Clinical cancer research : an official journal of the American Association for Cancer Research 15 ( 11 ) 3725 - 32 2009.05 [Refereed] [International journal]

PURPOSE: Gene transfer involving p53 is viewed as a potentially effective cancer therapy, but does not result in a good therapeutic response in all human cancers. The activation of p53 induces either cell cycle arrest or apoptosis. Cell cycle arrest in response to p53 activation is mediated primarily through the induction of the cyclin-dependent kinase inhibitor p21. Because p21 also has an inhibitory effect on p53-mediated apoptosis, the suppression of p53-induced p21 expression would be expected to result in the preferential induction of apoptosis. However, p21 also has tumor-suppressive properties. In this study, we developed an adenovirus vector that expresses p53 and suppresses p21 simultaneously to enhance p53-mediated apoptosis. EXPERIMENTAL DESIGN: We constructed a replication-deficient recombinant adenovirus (Ad-p53/miR-p21) that enabled cocistronic expression of the p53 protein and artificial microRNAs that targeted p21, and examined the therapeutic effectiveness of this vector in vitro and in vivo. RESULTS: The levels of p21 were significantly attenuated following infection with Ad-p53/miR-p21. In colorectal and hepatocellular carcinoma cells, infection with Ad-p53/miR-p21 augmented apoptosis as compared with an adenovirus that expressed p53 alone (Ad-p53/miR-control). Ad-p53/miR-p21 also significantly increased the chemosensitivity of cancer cells to adriamycin (doxorubicin). In a xenograft tumor model in nude mice, tumor volume was significantly decreased following the direct injection of Ad-p53/miR-p21 into the tumor, as compared with the injection of Ad-p53/miR-control. CONCLUSION: These results suggest that adenovirus-mediated transduction of p53 and p21-specific microRNAs may be useful for gene therapy of human cancers.

N-propionyl-cysteaminylphenol-magnetite conjugate (NPrCAP/M) is a nanoparticle for the targeted growth suppression of melanoma cells.

Makito Sato, Toshiharu Yamashita, Masae Ohkura, Yasue Osai, Akiko Sato, Tomoaki Takada, Hidenobu Matsusaka, Ichiro Ono, Yasuaki Tamura, Noriyuki Sato, Yasushi Sasaki, Akira Ito, Hiroyuki Honda, Kazumasa Wakamatsu, Shosuke Ito, Kowichi Jimbow

The Journal of investigative dermatology 129 ( 9 ) 2233 - 41 2009.03 [Refereed] [International journal]

A magnetite nanoparticle, NPrCAP/M, was produced for intracellular hyperthermia treatment of melanoma by conjugating N-propionyl-cysteaminylphenol (NPrCAP) with magnetite and used for the study of selective targeting and degradation of melanoma cells. NPrCAP/M, like NPrCAP, was integrated as a substrate in the oxidative reaction by mushroom tyrosinase. Melanoma, but not non-melanoma, cells incorporated larger amounts of iron than magnetite from NPrCAP/M. When mice bearing a B16F1 melanoma and a lymphoma on opposite flanks were given NPrCAP/M, iron was observed only in B16F1 melanoma cells and iron particles (NPrCAP/M) were identified within late-stage melanosomes by electron microscopy. When cells were treated with NPrCAP/M or magnetite and heated to 43 degrees C by an external alternating magnetic field (AMF), melanoma cells were degraded 1.7- to 5.4-fold more significantly by NPrCAP/M than by magnetite. Growth of transplanted B16 melanoma was suppressed effectively by NPrCAP/M-mediated hyperthermia, suggesting a clinical application of NPrCAP/M to lesional therapy for melanoma. Finally, melanoma cells treated with NPrCAP/M plus AMF showed little sub-G1 fraction and no caspase 3 activation, suggesting that the NPrCAP/M-mediated hyperthermia induced non-apoptotic cell death. These results suggest that NPrCAP/M may be useful in targeted therapy for melanoma by inducing non-apoptotic cell death after appropriate heating by the AMF.

Prediction of p53 target genes based on integrative analysis of chromatin- immunoprecipitated and sequenced tags,by using Galaxy,a web-based interactive platform for large-scale genome analysis

Mita H, Sasaki Y, Suzuki H, Idogawa M, Kashima L, Anbo N, Akashi H, Tatsumi H, Toyota M, Tokino T

Tumor Research ( Sapporo Medical University ) 43 1 - 23 2008.12 [Refereed]

Chromatin immunoprecipitation (ChIP) followed by sequencing of immunoprecipitated DNA fragments is the high-throughput method for identifying transcription factor binding sites. In one such method, ChIP-PET, paired-end ditags (PETs) derived from both ends of the immunoprecipitated DNA fragments are sequenced and mapped to the genome. We report here the prediction of p53 target genes by metaanalyzing tags of p53 ChIP-PET and by combining with other genomic annotations, using Galaxy, a web-based platform for large-scale genome analysis. We found 327 of p53 binding sites on the genome of 5-fluorouracil (5-FU)- treated HCT116 colon cancer cells by searching the total 65,509 PETs for PET clusters. The search for p53 target gene, which focused on PET clusters with computationally-predicted p53 binding motif, identified 20 of putative p53 target genes as well as 11 of known p53 targets. Another search for p53 target genes, which focused on PET clusters located within 50-kb flanking regions of transcription start sites of genes, identified 278 of Refseq genes, 79 of noncoding RNAs and 5 of microRNAs as p53 targets which included lots of known validated targets. Our results indicate that sequencing-based ChIP analysis combined with the existing genome annotation is effective method to predict p53 binding loci and target genes, and also show that the Galaxy platform is well-suited for multiple-type analyses and visualization of ChIP data, leading to functional annotation of transcription factor binding sites.

p53 family members regulate the expression of the apolipoprotein D gene.

Sasaki Y, Negishi H, Koyama R, Anbo N, Ohori K, Idogawa M, Mita H, Toyota M, Imai K, Shinomura Y, Tokino T

The Journal of biological chemistry 284 ( 2 ) 872 - 83 2008.11 [Refereed] [International journal]

Authorship： Lead author

p73 and p63 are members of the p53 gene family that play an important role in development and homeostasis, mainly by regulating transcription of a variety of genes. We report here that apolipoprotein D (apoD), a member of the lipocalin superfamily of lipid transport proteins, is a direct transcriptional target of the p53 family member genes. We found that the expression of apoD was specifically up-regulated by either TAp73 or TAp63 but not significantly by p53. In addition, apoD transcription is activated in response to cisplatin in a manner dependent on endogenous p73. By using small interference RNA designed to target p73, we demonstrated that silencing endogenous p73 abolishes induction of apoD transcription following cisplatin treatment. We also identified a p73/p63-binding site in the promoter of the apoD gene that is responsive to the p53 family members. The ectopic expression of TAp73 as well as the addition of recombinant human apoD to culture medium induced the osteoblastic differentiation of the human osteosarcoma cell line Saos-2, as assessed by alkaline phosphatase activity. Importantly, apoD knockdown abrogated p73-mediated alkaline phosphatase induction. Moreover, TAp73-mediated apoD expression was able to induce morphological differentiation, as well as expression of neuronal markers, in the human neuroblastoma cell line SH-SY5Y. These results suggest that apoD induction may mediate the activity of p73 in normal development.

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