Masayo Hosokawa

A genome-wide association study identifies three new susceptibility loci for ulcerative colitis in the Japanese population

Ulcerative colitis is one of the principal forms of inflammatory bowel disease with complex manifestations. Although previous studies have indicated that there is a genetic contribution to the pathogenesis of ulcerative colitis, the genes influencing susceptibility to the disease have not been fully determined. To identify genetic factors conferring risk of ulcerative colitis, here we conducted a two-stage genome-wide association study and subsequent replication study using 1,384 Japanese individuals with ulcerative colitis and 3,057 control subjects. In addition to the expected strong association with the major histocompatibility complex (MHC) region, we identified three new susceptibility loci: the immunoglobulin receptor gene FCGR2A (rs1801274, P = 1.56 × 10−12), a locus on chromosome 13q12 (rs17085007, P = 6.64 × 10−8) and the glycoprotein gene SLC26A3 (rs2108225, P = 9.50 × 10−8). rs1801274 is a nonsynonymous SNP of FCGR2A that is reported to have a critical effect on receptor binding affinity for IgG and to be associated with other autoimmune diseases. Our findings provide insight into the molecular pathogenesis of ulcerative colitis.

Overexpressed P-Cadherin/CDH3 Promotes Motility of Pancreatic Cancer Cells by Interacting with p120ctn and Activating Rho-Family GTPases

P-Cadherin/CDH3 belongs to the family of classic cadherins that are engaged in various cellular activities including motility, invasion, and signaling of tumor cells, in addition to cell adhesion. However, the biological roles of P-cadherin itself are not fully characterized. Based on information derived from a previous genome-wide cDNA microarray analysis of microdissected pancreatic ductal adenocarcinoma (PDAC), we focused on P-cadherin as one of the genes most strongly overexpressed in the great majority of PDACs. To investigate the consequences of overexpression of P-cadherin in terms of pancreatic carcinogenesis and tumor progression, we used a P-cadherin-deficient PDAC cell line, Panc-1, to construct a cell line (Panc1-CDH3) that stably overexpressed P-cadherin. Induction of P-cadherin in Panc1-CDH3 increased the motility of the cancer cells, but a blocking antibody against P-cadherin suppressed the motility in vitro. Overexpression of P-cadherin was strongly associated with cytoplasmic accumulation of one of the catenins, p120ctn, and cadherin switching in PDAC cells. Moreover, P-cadherin-dependent activation of cell motility was associated with activation of Rho GTPases, Rac1 and Cdc42, through accumulation of p120ctn in cytoplasm and cadherin switching. These findings suggest that overexpression of P-cadherin is likely to be related to the biological aggressiveness of PDACs; blocking of P-cadherin activity or its associated signaling could be a novel therapeutic approach for treatment of aggressive pancreatic cancers.

DNA methylation and histone deacetylation associated with silencing DAP kinase gene expression in colorectal and gastric cancers

Death-associated protein kinase is a positive regulator of programmed cell death induced by interferon γ. To investigate the role of epigenetic inactivation of death-associated protein kinase in gastrointestinal cancer, we examined the methylation status of the 5′ CpG island of the death-associated protein kinase gene. Methylation of the 5′ CpG island was detected in 3 of 9 colorectal and 3 of 17 gastric cancer cell lines, while among primary tumours, it was detected in 4 of 28 (14%) colorectal and 4 of 27 (15%) gastric cancers. By contrast, methylation of the edge of the CpG island was detected in virtually every sample examined. Death-associated protein kinase expression was diminished in four cell lines that showed dense methylation of the 5′ CpG island, and treatment with 5-aza-2′-deoxycitidine, a methyltransferase inhibitor, restored gene expression. Acetylation of histones H3 and H4 in the 5′ region of the gene was assessed by chromatin immunoprecipitation and was found to correlate directly with gene expression and inversely with DNA methylation. Thus, aberrant DNA methylation and histone deacetylation of the 5′ CpG island, but not the edge of the CpG island, appears to play a key role in silencing death-associated protein kinase expression in gastrointestinal malignancies.

A genome-wide association study identifies 2 susceptibility Loci for Crohn's disease in a Japanese population.

BACKGROUND & AIMS Crohns disease is an inflammatory bowel disease induced by multiple genetic and environmental factors. Genome-wide association studies have identified genetic factors that affect the risk for Crohns disease in European populations, but information from other ethnic groups is scarce. We therefore investigated genetic factors associated with Crohns disease in the Japanese population. METHODS We performed a genome-wide association study with 372 individuals with Crohns disease (cases) and 3389 controls, all from the Japanese population. To confirm identified associations, we performed a replication study with an independent panel of 1151 Crohns disease cases and 15,800 controls. We also performed an association analysis using genome-wide genotype imputation in the discovery cohort. RESULTS We confirmed associations of Crohns disease with variants in MHC (rs7765379, P = 2.11 × 10(-59)), TNFSF15 (rs6478106, P = 3.87 × 10(-45)), and STAT3 (rs9891119, P = 2.24 × 10(-14)). We identified 2 new susceptibility loci: on chromosome 4p14 (rs1487630, P = 2.40 × 10(-11); odds ratio, 1.33), and in the SLC25A15-ELF1-WBP4 region on 13q14 (rs7329174 in ELF1, P = 5.12 × 10(-9); odds ratio, 1.27). CONCLUSIONS In a genome-wide association study, we identified 2 new susceptibility loci for Crohns disease in a Japanese population. These findings could increase our understanding of the pathogenesis of Crohns disease.

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

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). Copyright

γ-Aminobutyric Acid (GABA) Stimulates Pancreatic Cancer Growth through Overexpressing GABAA Receptor π Subunit

;-Aminobutyric acid (GABA) functions primarily as an inhibitory neurotransmitter in the mature central nervous system, and GABA/GABA receptors are also present in nonneural tissues, including cancer, but their precise function in nonneuronal or cancerous cells has thus far been poorly defined. Through the genome-wide cDNA microarray analysis of pancreatic ductal adenocarcinoma (PDAC) cells as well as subsequent reverse transcription-PCR and Northern blot analyses, we identified the overexpression of GABA receptor P subunit (GABRP) in PDAC cells. We also found the expression of this peripheral type GABAA receptor subunit in few adult human organs. Knockdown of endogenous GABRP expression in PDAC cells by small interfering RNA attenuated PDAC cell growth, suggesting its essential role in PDAC cell viability. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRP-expressing PDAC cells, but not GABRP-negative cells, and GABAA receptor antagonists inhibited this growth-promoting effect by GABA. The HEK293 cells constitutively expressing exogenous GABRP revealed the growth-promoting effect of GABA treatment. Furthermore, GABA treatment in GABRP-positive cells increased intracellular Ca 2+ levels and activated the mitogenactivated protein kinase/extracellular signal–regulated kinase (MAPK/Erk) cascade. Clinical PDAC tissues contained a higher level of GABA than normal pancreas tissues due to the upregulation of glutamate decarboxylase 1 expression, suggesting their autocrine/paracrine growth-promoting effect in PDACs. These findings imply that GABA and GABRP could play important roles in PDAC development and progression, and that this pathway can be a promising molecular target for the development of new therapeutic strategies for PDAC. [Cancer Res 2007;67(20):9704–12]

Novel tumor marker REG4 detected in serum of patients with resectable pancreatic cancer and feasibility for antibody therapy targeting REG4

Pancreatic ductal adenocarcinoma (PDAC) shows the worst mortality rate among common malignancies, with a 5‐year survival rate of only 4%, and the majority of PDAC patients are diagnosed at an advanced stage in which no effective therapy is available at present. Although the proportion of curable cases is still not so high, surgical resection of early stage PDAC is the only way to cure the disease. Hence, establishment of a screening strategy to detect early stage PDAC by novel serological markers is required urgently, and development of novel molecular therapies for PDAC treatment is also eagerly expected. We here report overexpression of REG4, a new member of the regenerating islet‐derived (REG) family, in PDAC cells on the basis of genome‐wide cDNA microarray analysis as well as reverse transcription–polymerase chain reaction and immunohistochemical analysis. We also detected significant elevation of REG4 in the serum of some patients with early‐stage PDAC using our enzyme‐linked immunosorbent assay system, indicating the possibility of REG4 as a new serological marker of PDAC. Furthermore, we found that knockdown of endogenous REG4 expression in PDAC cell lines with small interfering RNA caused a decrease in cell viability. Concordantly, addition of recombinant REG4 to the culture medium enhanced growth of a PDAC cell line in a dose‐dependent manner. A monoclonal antibody against REG4 neutralized its growth‐promoting effects and attenuated significantly the growth of PDAC cells. These findings indicate that REG4 is a promising tumor marker to screen early‐stage PDAC, and also that neutralization of REG4 by the antibody may offer novel potential tools for the treatment of PDAC. (Cancer Sci 2006; 97: 1191–1197)

Oncogenic Role of KIAA0101 Interacting with Proliferating Cell Nuclear Antigen in Pancreatic Cancer

To isolate novel diagnostic markers and therapeutic targets for pancreatic cancer, we earlier did expression profile analysis of pancreatic cancer cells using a genome-wide cDNA microarray combined with microdissection. Among dozens of trans-activated genes in pancreatic cancer cells, this study focused on KIAA0101 whose overexpression in pancreatic cancer cells was validated by immunohistochemical analysis. KIAA0101 was previously identified as p15(PAF) [proliferating cell nuclear antigen (PCNA)-associated factor] to bind with PCNA; however, its function remains unknown. To investigate for the biological significance of KIAA0101 overexpression in cancer cells, we knocked down KIAA0101 by small interfering RNA (siRNA) in pancreatic cancer cells and found that the reduced expression by siRNA caused drastic attenuation of their proliferation as well as significant decrease in DNA replication rate. Concordantly, exogenous overexpression of KIAA0101 enhanced cancer cell growth, and NIH3T3 derivative cells expressing KIAA0101 revealed in vivo tumor formation, implying its growth-promoting and oncogenic property. We also showed that the expression of KIAA0101 was regulated tightly by the p53-p21 pathway. To consider the KIAA0101/PCNA interaction as a therapeutic target, we designed the cell-permeable 20-amino-acid dominant-negative peptide and found that it could effectively inhibit the KIAA0101/PCNA interaction and resulted in the significant growth suppression of cancer cells. Our results clearly implicated that suppression of the KIAA0101 and PCNA oncogenic activity, or the inhibition of KIAA0101/PCNA interaction, is likely to be a promising strategy to develop novel cancer therapeutic drugs.

EphA4 receptor, overexpressed in pancreatic ductal adenocarcinoma, promotes cancer cell growth

To isolate novel diagnostic markers and drug targets for pancreatic ductal adenocarcinoma (PDAC), we previously performed expression profile analysis of PDAC cells using a genome‐wide cDNA microarray combined with laser microdissection. Among dozens of up‐regulated genes identified in PDAC cells, we herein focused on one tyrosine kinase receptor, Eph receptor A4 (EphA4), as a molecular target for PDAC therapy. Immunohistochemical analysis validated EphA4 overexpression in approximately half of the PDAC tissues. To investigate its biological function in PDAC cells, we knocked down EphA4 expression by siRNA, which drastically attenuated PDAC cell viability. In concordance with the siRNA experiment, PDAC‐derivative cells that were designed to constitutively express exogenous EphA4 showed a more rapid growth rate than cells transfected with mock vector, suggesting a growth‐promoting effect of EphA4 on PDAC cells. Furthermore, the expression analysis for ephrin ligand family members indicated the coexistence of ephrinA3 ligand in PDAC cells with EphA4 receptor, and knockdown of ephrinA3 by siRNA also attenuated PDAC cell viability. These results suggest that the EphA4–ephrinA3 pathway is likely to be a promising molecular target for pancreatic cancer therapy. (Cancer Sci 2006; 97: 1211–1216)

Tumour matrilysin expression predicts metastatic potential of stage I (pT1) colon and rectal cancers

Background and aims: Nodal metastases are indisputable determinants of prognosis for colon and rectal cancer. Using classical histological criteria, many attempts to predict nodal metastasis have failed, preventing the adequate management of stage I (pT1) cancer. We investigated the role of tumour matrilysin in predicting metastatic potential, and discuss its potential use in individualising treatment of pT1 colon and rectal cancer. Methods: The gene signature associated with nodal metastasis was investigated by cDNA array in 24 colon and rectal cancers. We studied 494 colon and rectal cancer patients to identify risk factors for nodal metastasis and evaluated the potential to predict nodal metastasis by either the logistic regression model or the Bayesian neural network model with built-in matrilysin. We then inferred possible causality of nodal metastasis from structural equation modelling. Results: cDNA array revealed that matrilysin was maximally upregulated in the metastasis signature identified. Tumour matrilysin expression emerged as a stage independent risk factor for nodal metastasis, resulting in a similar predictive performance in receiver operating characteristic curve analysis in the two models. A Bayesian approach called automatic relevance determination identified matrilysin as one of the most relevant predictors examined. Structural equation modelling suggested possible direct causality between matrilysin and nodal metastasis. Conclusions: We have provided evidence that tumour matrilysin expression is a promising biomarker predicting nodal metastasis of colon and rectal cancer. Analysis of tumour matrilysin expression would help clinicians achieve the goal of individualised cancer treatment based on the metastatic potential of pT1 colon and rectal cancer.