Details of a Researcher - SASAKI Yasushi

Papers - SASAKI Yasushi

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TET1 Depletion Induces Aberrant CpG Methylation in Colorectal Cancer Cells.

Kai M, Niinuma T, Kitajima H, Yamamoto E, Harada T, Aoki H, Maruyama R, Toyota M, Sasaki Y, Sugai T, Tokino T, Nakase H, Suzuki H

PloS one 11 ( 12 ) e0168281 2016.12 [Refereed] [International journal]

Aberrant DNA methylation is commonly observed in colorectal cancer (CRC), but the underlying mechanism is not fully understood. 5-hydroxymethylcytosine levels and TET1 expression are both reduced in CRC, while epigenetic silencing of TET1 is reportedly associated with the CpG island methylator phenotype. In the present study, we aimed to clarify the relationship between loss of TET1 and aberrant DNA methylation in CRC. Stable TET1 knockdown clones were established using Colo320DM cells, which express high levels of TET1, and HCT116 cells, which express TET1 at a level similar to that in normal colonic tissue. Infinium HumanMethylation450 BeadChip assays revealed increased levels of 5-methylcytosine at more than 10,000 CpG sites in TET1-depleted Colo320DM cells. Changes in DNA methylation were observed at various positions within the genome, including promoters, gene bodies and intergenic regions, and the altered methylation affected expression of a subset of genes. By contrast, TET1 knockdown did not significantly affect DNA methylation in HCT116 cells. However, TET1 depletion was associated with attenuated effects of 5-aza-2'-deoxycytidine on gene expression profiles in both cell lines. These results suggest that loss of TET1 may induce aberrant DNA methylation and may attenuate the effect of 5-aza-2'-deoxycytidine in CRC cells.

Systemic Prophylactic Antibiotics for the Modified Introducer Method for Percutaneous Endoscopic Gastrostomy: A Prospective, Randomized, Double-Blind Study.

Yasushi Adachi, Kimishige Akino, Hiroaki Mita, Takefumi Kikuchi, Kentaro Yamashita, Yasushi Sasaki, Yoshiaki Arimura, Takao Endo

Journal of clinical gastroenterology 50 ( 9 ) 727 - 32 2016.10 [Refereed] [International journal]

Percutaneous endoscopic gastrostomy (PEG) is the most common method of enteral nutrition in patients who require long-term tube feeding. According to meta-analyses, administration of systemic prophylactic antibiotics for PEG reduces peristomal infection. However, with several recent developments in the procedure and instruments, the risk of infection might have been reduced. The aim of this study was to evaluate the use of systemic antibiotic prophylaxis for a modified introducer method of PEG.This prospective, randomized, double-blind trial assessed 278 patients undergoing PEG for inclusion. Ninety-one patients with an indication for PEG who gave informed consent to participate were randomized. Forty-six patients received prophylactic ampicillin and 45 patients received a placebo. A modified introducer method of PEG using a Seldinger PEG kit was performed. The primary outcome was the occurrence of clinically evident wound infection within 3 days after PEG.Wound infection within 3 days was observed in none in the prophylaxis group and in 1 patient in the control group (P=0.4945). There was no significant difference between 2 groups in the other parameters, including peristomal infection within 7 days, overall infection, white blood cell counts, C-reactive protein level, and successive rate of finishing antibiotics.For wound infection within 3 days, noninferiority of the placebo group to the antibiotics group was preliminarily suggested with our criteria, but not for peristomal infection within 7 days. More strict criteria for noninferiority should be examined in a further large sample study.

DOI DOI2 PubMed

Plasticity of lung cancer stem-like cells is regulated by the transcription factor HOXA5 that is induced by oxidative stress.

Saijo H, Hirohashi Y, Torigoe T, Horibe R, Takaya A, Murai A, Kubo T, Kajiwara T, Tanaka T, Shionoya Y, Yamamoto E, Maruyama R, Nakatsugawa M, Sato N

Oncotarget ( Impact Journals, LLC ) 7 ( 31 ) 50043 - 50056 2016.08 [Refereed]

The effect of forced expression of mutated K-RAS gene on gastrointestinal cancer cell lines and the IGF-1R targeting therapy.

Matsunaga Y, Adachi Y, Sasaki Y, Koide H, Motoya M, Nosho K, Takagi H, Yamamoto H, Sasaki S, Arimura Y, Tokino T, Carbone DP, Imai K, Shinomura Y

Molecular carcinogenesis 56 ( 2 ) 515 - 526 2016.06 [Refereed] [International journal]

Mutation in K-RAS (K-RAS-MT) plays important roles in both cancer progression and resistance to anti-epidermal growth factor receptor (EGFR) therapy in gastrointestinal tumors. Insulin-like growth factor-1 receptor (IGF-1R) signaling is required for carcinogenicity and progression of many tumors as well. We have previously shown successful therapy for gastrointestinal cancer cell lines bearing a K-RAS mutation using an anti-IGF-1R monoclonal antibody. In this study, we sought to evaluate effects of forced K-RAS-MT expression on gastrointestinal cancer cell lines representing a possible second resistance mechanism for anti-EGFR therapy and IGF-1R-targeted therapy for these transfectants. We made stable transfectants of K-RAS-MT in two gastrointestinal cancer cell lines, colorectal RKO and pancreatic BxPC-3. We assessed the effect of forced expression of K-RAS-MT on proliferation, apoptosis, migration, and invasion in gastrointestinal cancer cells. Then we assessed anti-tumor effects of dominant negative IGF-1R (IGF-1R/dn) and an IGF-1R inhibitor, picropodophyllin, on the K-RAS-MT transfectants. Overexpression of K-RAS-MT in gastrointestinal cancer cell lines led to more aggressive phenotypes, with increased proliferation, decreased apoptosis, and increased motility and invasion. IGF-1R blockade suppressed cell growth, colony formation, migration, and invasion, and up-regulated chemotherapy-induced apoptosis of gastrointestinal cancer cells, even when K-RAS-MT was over-expressed. IGF-1R blockade inhibited the Akt pathway more than the extracellular signal-regulated kinase (ERK) pathway in the K-RAS-MT transfectants. IGF-1R/dn, moreover, inhibited the growth of murine xenografts expressing K-RAS-MT. Thus, K-RAS-MT might be important for progressive phonotype observed in gastrointestinal cancers. IGF-1R decoy is a candidate molecular therapeutic approach for gastrointestinal cancers even if K-RAS is mutated. © 2016 Wiley Periodicals, Inc.

Genomic characterization of esophageal squamous cell carcinoma: Insights from next-generation sequencing

Yasushi Sasaki, Miyuki Tamura, Ryota Koyama, Takafumi Nakagaki, Yasushi Adachi, Takashi Tokino

World Journal of Gastroenterology 22 ( 7 ) 2284 - 2293 2016.02 [International journal]

Authorship： Lead author

© The Author(s) 2016. Two major types of cancer occur in the esophagus: squamous cell carcinoma, which is associated with chronic smoking and alcohol consumption, and adenocarcinoma, which typically arises in gastric reflux-associated Barrett's esophagus. Although there is increasing incidence of esophageal adenocarcinoma in Western counties, esophageal squamous cell carcinoma (ESCC) accounts for most esophageal malignancies in East Asia, incluDing China and Japan. Technological advances allowing for massively parallel, high-throughput next-generation sequencing (NGS) of DNA have enabled comprehensive characterization of somatic mutations in large numbers of tumor samples. Recently, several studies were published in which whole exome or whole genome sequencing was performed in ESCC tumors and compared with matched normal DNA. Mutations were validated in several genes, incluDing in TP53 , CDKN2A , FAT1 , NOTCH1 , PIK3CA , KMT2D and NFE2L2 , which had been previously implicated in ESCC. Several new recurrent alterations have also been identified in ESCC. Combining the clinicopathological characteristics of patients with information obtained from NGS studies may lead to the development of effective diagnostic and therapeutic approaches for ESCC. As this research becomes more prominent, it is important that gastroenterologist become familiar with the various NGS technologies and the results generated using these methods. In the present study, we describe recent research approaches using NGS in ESCC.

Identification and characterization of the intercellular adhesion molecule-2 gene as a novel p53 target

Yasushi Sasaki, Miyuki Tamura, Kousuke Takeda, Kazuhiro Ogi, Takafumi Nakagaki, Ryota Koyama, Masashi Idogawa, Hiroyoshi Hiratsuka, Takashi Tokino

Oncotarget ( (一社)日本癌学会 ) 7 ( 38 ) 61426 - 61437 2016 [Refereed] [International journal]

Authorship： Lead author , Corresponding author

The p53 tumor suppressor inhibits cell growth through the activation of both cell cycle arrest and apoptosis, which maintain genome stability and prevent cancer development. Here, we report that intercellular adhesion molecule-2 (ICAM2) is transcriptionally activated by p53. Specifically, ICAM2 is induced by the p53 family and DNA damage in a p53-dependent manner. We identified a p53 binding sequence located within the ICAM2 gene that is responsive to wild-type p53, TAp73, and TAp63. In terms of function, we found that the ectopic expression of ICAM2 inhibited cancer cell migration and invasion. In addition, we demonstrated that silencing endogenous ICAM2 in cancer cells caused a marked increase in extracellular signal-regulated kinase (ERK) phosphorylation levels, suggesting that ICAM2 inhibits migration and invasion of cancer cells by suppressing ERK signaling. Moreover, ICAM2 is underexpressed in human cancer tissues containing mutant p53 as compared to those with wild-type p53. Notably, the decreased expression of ICAM2 is associated with poor survival in patients with various cancers. Our findings demonstrate that ICAM2 induction by p53 has a key role in inhibiting migration and invasion.

Molecular diagnostics of a single drug-resistant multiple myeloma case using targeted next-generation sequencing

Hiroshi Ikeda, Kazuya Ishiguro, Tetsuyuki Igarashi, Yuka Aoki, Toshiaki Hayashi, Tadao Ishida, Yasushi Sasaki, Takashi Tokino, Yasuhisa Shinomura

OncoTargets and Therapy 8 2805 - 2815 2015.10 [Refereed] [International journal]

Authorship： Corresponding author

© 2015 Ikeda et al. A 69-year-old man was diagnosed with IgG λ-type multiple myeloma (MM), Stage II in October 2010. He was treated with one cycle of high-dose dexamethasone. After three cycles of bortezomib, the patient exhibited slow elevations in the free light-chain levels and developed a significant new increase of serum M protein. Bone marrow cytogenetic analysis revealed a complex karyotype characteristic of malignant plasma cells. To better understand the molecular pathogenesis of this patient, we sequenced for mutations in the entire coding regions of 409 cancer-related genes using a semiconductor-based sequencing platform. Sequencing analysis revealed eight nonsynonymous somatic mutations in addition to several copy number variants, including CCND1 and RB1. These alterations may play roles in the pathobiology of this disease. This targeted next-generation sequencing can allow for the prediction of drug resistance and facilitate improvements in the treatment of MM patients.

Epigenetic silencing of NTSR1 is associated with lateral and noninvasive growth of colorectal tumors.

Kamimae S, Yamamoto E, Kai M, Niinuma T, Yamano HO, Nojima M, Yoshikawa K, Kimura T, Takagi R, Harada E, Harada T, Maruyama R, Sasaki Y, Tokino T, Suzuki H

Oncotarget 6 ( 30 ) 29975 - 90 2015.10 [Refereed] [International journal]

Our aim was to identify DNA methylation changes associated with the growth pattern and invasiveness of colorectal cancers (CRCs). Comparison of the methylation statuses of large (≥ 20 mm in diameter along the colonic surface) noninvasive tumors (NTs) and small (<20 mm in diameter along the colonic surface) invasive tumors (ITs) using CpG island microarray analysis showed neurotensin receptor 1 (NTSR1) to be hypermethylated in large NTs. Quantitative bisulfite pyrosequencing revealed that NTSR1 is frequently methylated in colorectal tumors, with large NTs exhibiting the highest methylation levels. The higher NTSR1 methylation levels were associated with better prognoses. By contrast, NTSR1 copy number gains were most frequent among small ITs. Methylation of NTSR1 was associated with the gene's silencing in CRC cell lines, whereas ectopic expression of NTSR1 promoted proliferation and invasion by CRC cells. Analysis of primary tumors composed of adenomatous and malignant portions revealed that NTSR1 is frequently methylated in the adenomatous portion, while methylation levels are generally lower in the cancerous portions. These results suggest that NTSR1 methylation is associated with lateral and noninvasive growth of colorectal tumors, while low levels of methylation may contribute to the malignant potential through activation of NTSR1. Our data also indicate that NTSR1 methylation may be a prognostic biomarker in CRC.

CRKL oncogene is downregulated by p53 through miR-200s

Miyuki Tamura, Yasushi Sasaki, Kenta Kobashi, Kousuke Takeda, Takafumi Nakagaki, Masashi Idogawa, Takashi Tokino

Cancer Science 106 ( 8 ) 1033 - 1040 2015.08 [Refereed] [International journal]

Authorship： Corresponding author

© 2015 The Authors. Tumor suppressive miRNAs that target oncogenes are frequently downregulated in cancers, and this downregulation leads to oncogene pathway activation. Thus, tumor suppressive miRNAs and their target oncogenes have been proposed as useful targets in cancer treatment. miR-200 family downregulation has been reported in cancer progression and metastasis. The miR-200 family consists of two gene clusters, miR-200b/200a/429 and miR-200c/141, which are located on human chromosomes 1 and 12, respectively. Here, we identified that p53 response elements are located around both clusters of the miR-200 family and confirmed that miR-200s are transcriptional targets of the p53 family. In silico analyses of miRNA targets established the CRKL oncogene as a potential target for miR-200b/200c/429. Moreover, miR-200b/200c/429 inhibited CRKL mRNA and protein expression by directly targeting its 3′-UTR region. Importantly, endogenous CRKL expression was decreased in cancer cells through the introduction of p53 family and endogenous p53 activation. Moreover, the downregulation of CRKL by siRNA inhibited cancer cell growth. The Oncomine database demonstrates that CRKL is overexpressed in a subset of cancer types. Furthermore, CRKL is significantly overexpressed in primary breast cancer tissues harboring mutant TP53. Our results demonstrate that the p53 target miR-200b/200c/429 miRNAs are negative regulators of the CRKL oncogene.

Endoscopic diagnosis and clinical management for serrated lesions of the large intestine

Hiroo Yamano, Yoshihito Tanaka, Hiroo Matsushita, Kenjiro Yoshikawa, Ryo Takagi, Eiji Harada, Michiko Nakaoka, Ryogo Himori, Yuko Yoshida, Daiki Tanaka, Kentaro Sato, Yasushi Imai, Tamotsu Sugai, Makoto Eizuka, Eiichiro Yamamoto, Hironori Aoki, Hiromu Suzuki

Journal of Japanese Society of Gastroenterology ( Japanese Society of Gastroenterology ) 112 ( 4 ) 676 - 682 2015 [Refereed]

Forkhead transcription factor FOXF1 is a novel target gene of the p53 family and regulates cancer cell migration and invasiveness

M. Tamura, Y. Sasaki, R. Koyama, K. Takeda, M. Idogawa, T. Tokino

Oncogene 33 ( 40 ) 4837 - 4846 2014.10 [Refereed]

Authorship： Corresponding author

© 2014 Macmillan Publishers Limited. P53 is an established tumor suppressor that can activate the transcription of multiple target genes. Recent evidence suggests that p53 may contribute to the regulation of cell invasion and migration. In this study, we show that the forkhead box transcription factor FOXF1 is a novel target of the p53 family because FOXF1 is upregulated by p53, TAp73 and TAp63. We show that FOXF1 is induced upon DNA damage in a p53-dependent manner. Furthermore, we identified a response element located within the FOXF1 gene that is responsive to wild-type p53, TAp73β and TAp63γ. The ectopic expression of FOXF1 inhibited cancer cell invasion and migration, whereas the inactivation of FOXF1 stimulated cell invasion and migration. We also show that FOXF1 regulates the transcriptional activity of E-cadherin (CDH1) by acting on its FOXF1 consensus binding site located upstream of the E-cadherin gene. Collectively, our results show that FOXF1 is a p53 family target gene, and our data suggest that FOXF1 and p53 form a portion of a regulatory transcriptional network that appears to have an important role in cancer cell invasion and migration.

Array-based genome-wide RNAi screening to identify shRNAs that enhance p53-related apoptosis in human cancer cells.

Idogawa M, Ohashi T, Sugisaka J, Sasaki Y, Suzuki H, Tokino T

Oncotarget 5 ( 17 ) 7540 - 8 2014.09 [Refereed] [International journal]

p53 transduction is a potentially effective cancer therapy but does not result in a good therapeutic response in all human cancers due to resistance to apoptosis. To discover factors that overcome resistance to p53-induced apoptosis, we attempted to identify RNAi sequences that enhance p53-induced apoptosis. We screened a genome-wide lentiviral shRNA library in liver cancer Huh-7 and pancreatic cancer Panc-1 cells, both of which resist p53-induced apoptosis. After the infection of adenovirus expressing p53 or LacZ as a control, shRNA-treated populations were analyzed by microarray. We identified shRNAs that were significantly decreased in p53-infected cells compared with control cells. Among these shRNAs, shRNA-58335 was markedly decreased in both cancer cell lines tested. shRNA-58335 enhanced p53-related apoptosis in vitro and augmented the inhibitory effect of adenoviral p53 transduction on tumor growth in vivo. Furthermore, the enhanced apoptotic response by shRNA-58335 was also confirmed by treatment with PRIMA-1, which reactivates mutant p53, instead of adenoviral p53 transduction. We found that shRNA-58335 evokes the apoptotic response following p53 transduction or functional restoration of p53 with a small molecule drug in cancer cells resistant to p53-induced apoptosis. The combination of p53 restoration and RNAi-based drugs is expected to be a promising novel cancer therapy.

MicroRNA-31 expression in relation to BRAF mutation, CpG island methylation and colorectal continuum in serrated lesions.

Ito M, Mitsuhashi K, Igarashi H, Nosho K, Naito T, Yoshii S, Takahashi H, Fujita M, Sukawa Y, Yamamoto E, Takahashi T, Adachi Y, Nojima M, Sasaki Y, Shinomura Y

International journal of cancer 135 ( 11 ) 2507 - 15 2014.04 [Refereed] [International journal]

The CpG island methylator phenotype (CIMP) is a distinct form of epigenomic instability. Many CIMP-high colorectal cancers (CRCs) with BRAF mutation are considered to arise from serrated pathway. We recently reported that microRNA-31 (miR-31) is associated with BRAF mutation in colorectal tumors. Emerging new approaches have revealed gradual changes in BRAF mutation and CIMP-high throughout the colorectum in CRCs. Here, we attempted to identify a possible association between miR-31 and epigenetic features in serrated pathway, and hypothesized that miR-31 supports the "colorectal continuum" concept. We evaluated miR-31 expression, BRAF mutation and epigenetic features including CIMP status in 381 serrated lesions and 222 non-serrated adenomas and examined associations between them and tumor location (rectum; sigmoid, descending, transverse and ascending colon and cecum). A significant association was observed between high miR-31 expression and CIMP-high status in serrated lesions with BRAF mutation (p = 0.0001). In contrast, miR-31 was slightly but insignificantly associated with CIMP status in the cases with wild-type BRAF. miR-31 expression in sessile serrated adenomas (SSAs) with cytological dysplasia was higher than that in SSAs, whereas, no significant difference was observed between traditional serrated adenomas (TSAs) and TSAs with high-grade dysplasia. The frequency of miR-31, BRAF mutation CIMP-high and MLH1 methylation increased gradually from the rectum to cecum in serrated lesions. In conclusion, miR-31 expression was associated with CIMP-high status in serrated lesions with BRAF mutation. Our data also suggested that miR-31 plays an important role in SSA evolution and may be a molecule supporting the colorectal continuum.

Identification and analysis of large intergenic non-coding RNAs regulated by p53 family members through a genome-wide analysis of p53-binding sites.

Idogawa M, Ohashi T, Sasaki Y, Maruyama R, Kashima L, Suzuki H, Tokino T

Human Molecular Genetics 23 ( 11 ) 2847 - 57 2014.01 [Refereed] [International journal]

p53 is one of the most important known tumor suppressor genes, and it is inactivated in approximately half of human cancers. p53 family members execute various functions, such as apoptosis induction and cell cycle arrest, by modulating transcriptional regulation. Therefore, the direct transcriptional targets of the p53 family must be explored to elucidate the functional mechanisms of family members. To identify the direct transcriptional targets of p53 family members, we performed chromatin immunoprecipitation together with next-generation sequencing (ChIP-seq) and searched for p53-binding motifs across the entire human genome. Among the identified ChIP-seq peaks, approximately half were located in an intergenic region. Therefore, we assumed large intergenic non-coding RNAs (lincRNAs) to be major targets of the p53 family. Recent reports have revealed that lincRNAs play an important role in various biological and pathological processes, such as development, differentiation, stemness and carcinogenesis. Through a combination of ChIP-seq and in silico analyses, we found 23 lincRNAs that are upregulated by the p53 family. Additionally, knockdown of specific lincRNAs modulated p53-induced apoptosis and promoted the transcription of a gene cluster. Our results suggest that p53 family members, and lincRNAs constitute a complex transcriptional network involved in various biological functions and tumor suppression.

AKR1B10, a transcriptional target of p53, is downregulated in colorectal cancers associated with poor prognosis.

Ohashi T, Idogawa M, Sasaki Y, Suzuki H, Tokino T

Molecular cancer research ( (一社)日本癌学会 ) 11 ( 12 ) 1554 - 63 2013.10 [Refereed] [International journal]

UNLABELLED: p53 is one of the most important tumor suppressor genes, and it is frequently inactivated in various cancers. p53 modulates various cellular functions, such as apoptosis and cell-cycle arrest via transcriptional regulation. Recently, p53 has been reported to be involved in a wide range of cellular metabolic pathways, including glycolysis, oxidative phosphorylation, glutaminolysis, and the antioxidant response. To understand the functional mechanism of p53, it is important to find out the direct transcriptional targets of p53. In this study, aldo-keto reductase family 1, member B10 (AKR1B10) was identified as a direct target of the p53 family by cDNA microarray analysis after comparing the mRNA expression of control and H1299 cells that overexpressed with p53 family members. In addition, we found that the expression of AKR1B10 was significantly decreased in colorectal cancers and adenomas as compared with normal colon tissues. Knockdown of AKR1B10 significantly inhibited p53-induced apoptosis in colorectal cancer cells, whereas the overexpression of AKR1B10 enhanced p53-induced apoptosis and inhibited tumor proliferation in vivo. Furthermore, low expression of AKR1B10 in colon cancer patients was correlated with decreased survival and poor prognosis. These results suggest that decreased expression of AKR1B10 could disrupt the tumor suppressive function of p53, which result in decreased survival in colorectal cancer patients. In summary, AKR1B10 may be a novel prognostic predictor and a novel therapeutic target for colorectal cancer. IMPLICATIONS: AKR1B10, a transcriptional target of p53, is also a novel prognostic and therapeutic molecule in colorectal cancer.

The effect of IGF-I receptor blockade for human esophageal squamous cell carcinoma and adenocarcinoma.

Yasushi Adachi, Hirokazu Ohashi, Arisa Imsumran, Hiroyuki Yamamoto, Yasutaka Matsunaga, Hiroaki Taniguchi, Katsuhiko Nosho, Hiromu Suzuki, Yasushi Sasaki, Yoshiaki Arimura, David P Carbone, Kohzoh Imai, Yasuhisa Shinomura

Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 35 ( 2 ) 973 - 85 2013.09 [Refereed] [International journal]

Insulin-like growth factor-I receptor (IGF-IR) signaling is required for carcinogenicity and tumor development, and this pathway has not been well studied in human esophageal carcinomas. Esophageal cancer is one of the human cancers with the worst prognosis and has two main histologies: squamous cell carcinomas (ESCC) and adenocarcinoma (EAC). Previously, we have reported that detection of the IGF axis may be useful for the prediction of recurrence and poor prognosis of ESCC. We have also shown the successful therapy for several gastrointestinal cancers using recombinant adenoviruses expressing dominant negative IGF-IR (ad-IGF-IR/dn). The aim of this study is to develop potential targeted therapeutics to IGF-IR and to assess the effect of IGF-IR blockade in both of these types of esophageal cancer. We determined immunohistochemical expression of IGF-IR in a tissue microarray. We then assessed the effect of IGF-IR blockade on signal transduction, proliferation, apoptosis, and motility. Ad-IGF-IR/dn, a tyrosine kinase inhibitor, BMS-536924, and adenovirus expressing shRNA for IGF-IR were used. IGF-IR expression was common in both tumor types but not in normal tissues. IGF-IR was detected in metastatic sites at similar levels compared to the primary site. IGF-IR inhibition suppressed proliferation and colony formation in both cancers. IGF-IR blockades up-regulated both stress- and chemotherapy-induced apoptosis and reduced migration. Although IGF-IR/dn blocked ligand-induced activation of Akt-1 mainly, BMS-536924 effectively blocked both activation of Akt and MAPK. The IGF axis might play a key role in tumor progression of esophageal carcinomas. The IGF-IR targeting strategies might thus be useful anticancer therapeutics for human esophageal malignancies.

Molecular dissection of premalignant colorectal lesions reveals early onset of the CpG island methylator phenotype.

Eiichiro Yamamoto, Hiromu Suzuki, Hiro-o Yamano, Reo Maruyama, Masanori Nojima, Seiko Kamimae, Takeshi Sawada, Masami Ashida, Kenjiro Yoshikawa, Tomoaki Kimura, Ryo Takagi, Taku Harada, Ryo Suzuki, Akiko Sato, Masahiro Kai, Yasushi Sasaki, Takashi Tokino, Tamotsu Sugai, Kohzoh Imai, Yasuhisa Shinomura, Minoru Toyota

The American journal of pathology 181 ( 5 ) 1847 - 61 2012.09 [Refereed] [International journal]

The concept of the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC) is widely accepted, although the timing of its occurrence and its interaction with other genetic defects are not fully understood. Our aim in this study was to unravel the molecular development of CIMP cancers by dissecting their genetic and epigenetic signatures in precancerous and malignant colorectal lesions. We characterized the methylation profile and BRAF/KRAS mutation status in 368 colorectal tissue samples, including precancerous and malignant lesions. In addition, genome-wide copy number aberrations, methylation profiles, and mutations of BRAF, KRAS, TP53, and PIK3CA pathway genes were examined in 84 colorectal lesions. Genome-wide methylation analysis of CpG islands and selected marker genes revealed that CRC precursor lesions are in three methylation subgroups: CIMP-high, CIMP-low, and CIMP-negative. Interestingly, a subset of CIMP-positive malignant lesions exhibited frequent copy number gains on chromosomes 7 and 19 and genetic defects in the AKT/PIK3CA pathway genes. Analysis of mixed lesions containing both precancerous and malignant components revealed that most aberrant methylation is acquired at the precursor stage, whereas copy number aberrations are acquired during the progression from precursor to malignant lesion. Our integrative genomic and epigenetic analysis suggests early onset of CIMP during CRC development and indicates a previously unknown CRC development pathway in which epigenetic instability associates with genomic alterations.

A novel approach to cancer treatment using structural hybrids of the p53 gene family.

Sasaki Y, Oshima Y, Koyama R, Tamura M, Kashima L, Idogawa M, Yamashita T, Toyota M, Imai K, Shinomura Y, Tokino T

Cancer gene therapy 2012.09 [Refereed]

Authorship： Lead author

CLCA2, a target of the p53 family, negatively regulates cancer cell migration and invasion.

Sasaki Y, Koyama R, Maruyama R, Hirano T, Tamura M, Sugisaka J, Suzuki H, Idogawa M, Shinomura Y, Tokino T

Cancer biology & therapy 13 ( 14 ) 1512 - 21 2012.09 [Refereed] [International journal]

Authorship： Lead author

The tumor suppressor p53 transcriptionally regulates a number of genes that are involved in cell-cycle inhibition, apoptosis and the maintenance of genetic stability. Recent studies suggest that p53 also contributes to the regulation of cell migration and invasion. Here, we show that human chloride channel accessory-2 (CLCA2) is a target gene of the p53 family (p53, p73 and p63). CLCA2 is induced by DNA damage in a p53-dependent manner. The p53 family proteins activate the CLCA2 promoter by binding directly to the conserved consensus p53-binding site present in the CLCA2 promoter. In terms of function, ectopic expression of CLCA2 inhibited cancer cell migration. In contrast, silencing CLCA2 with siRNA stimulated cancer cell migration and invasion. We also found that inactivation of CLCA2 enhanced the expression of focal adhesion kinase (FAK), as well as its promoter activation. A small-molecule FAK inhibitor reduced the effect of CLCA2 siRNA on cell migration and invasion, suggesting that CLCA2 inhibits cancer cell migration and invasion through suppression of the FAK signaling pathway. Furthermore, there was an inverse correlation between CLCA2 and FAK expression in 251 human breast cancer tissues. These results strongly suggest that CLCA2 is involved in the p53 tumor suppressor network and has a significant effect on cell migration and invasion.

Heat shock enhances the expression of cytotoxic granule proteins and augments the activities of tumor-associated antigen-specific cytotoxic T lymphocytes.

Takahashi A, Torigoe T, Tamura Y, Kanaseki T, Tsukahara T, Sasaki Y, Kameshima H, Tsuruma T, Hirata K, Tokino T, Hirohashi Y, Sato N

Cell Stress & Chaperones 17 ( 6 ) 757 - 63 2012.07 [Refereed] [International journal]

Focal inflammation causes systemic fever. Cancer hyperthermia therapy results in shrinkage of tumors by various mechanisms, including induction of adaptive immune response. However, the physiological meaning of systemic fever and mechanisms of tumor shrinkage by hyperthermia have not been completely understood. In this study, we investigated how heat shock influences the adaptive immune system. We established a cytotoxic T lymphocyte (CTL) clone (#IM29) specific for survivin, one of the tumor-associated antigens (TAAs), from survivin peptide-immunized cancer patients' peripheral blood, and the CTL activities were investigated in several temperature conditions (37-41 °C). Cytotoxicity and IFN-γ secretion of CTL were greatest under 39 °C condition, whereas they were minimum under 41 °C. To address the molecular mechanisms of this phenomenon, we investigated the apoptosis status of CTLs, expression of CD3, CD8, and TCRαβ by flow cytometry, and expression of perforin, granzyme B, and Fas ligand by western blot analysis. The expression of perforin and granzyme B were upregulated under temperature conditions of 39 and 41 °C. On the other hand, CTL cell death was induced under 41 °C condition with highest Caspase-3 activity. Therefore, the greatest cytotoxicity activity at 39 °C might depend on upregulation of cytotoxic granule proteins including perforin and granzyme B. These results suggest that heat shock enhances effector phase of the adaptive immune system and promotes eradication of microbe and tumor cells.

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