Keiji Ozeki

Mechanisms of Cisplatin-Induced Apoptosis and of Cisplatin Sensitivity: Potential of BIN1 to Act as a Potent Predictor of Cisplatin Sensitivity in Gastric Cancer Treatment

Cisplatin is the most important and efficacious chemotherapeutic agent for the treatment of advanced gastric cancer. Cisplatin forms inter- and intrastrand crosslinked DNA adducts and its cytotoxicity is mediated by propagation of DNA damage recognition signals to downstream pathways involving ATR, p53, p73, and mitogen-activated protein kinases, ultimately resulting in apoptosis. Cisplatin resistance arises through a multifactorial mechanism involving reduced drug uptake, increased drug inactivation, increased DNA damage repair, and inhibition of transmission of DNA damage recognition signals to the apoptotic pathway. In addition, a new mechanism has recently been revealed, in which the oncoprotein c-Myc suppresses bridging integrator 1 (BIN1), thereby releasing poly(ADP-ribose)polymerase 1, which results in increased DNA repair activity and allows cancer cells to acquire cisplatin resistance. The present paper focuses on the molecular mechanisms of cisplatin-induced apoptosis and of cisplatin resistance, in particular on the involvement of BIN1 in the maintenance of cisplatin sensitivity.

Establishment of a long-term three-dimensional primary culture of mouse glandular stomach epithelial cells within the stem cell niche

Compared to the small intestine and colon, little is known about stem cells in the stomach because of a lack of specific stem cell markers and an in vitro system that allows long-term culture. Here we describe a long-term three-dimensional (3D) primary gastric culture system within the stem cell niche. Glandular stomach cells from neonatal mice cultured in collagen gel yielded expanding sphere-like structures for 3months. The wall of the gastrospheres consisted of a highly polarized epithelial monolayer with an outer lining of myofibroblasts. The epithelial cells showed a tall columnar cell shape, basal round nuclei, and mucus-filled cytoplasm as well as expression of MUC5AC, indicating differentiation into gastric surface mucous cells. These cells demonstrated the features of fully differentiated gastric surface mucous cells such as microvilli, junctional complexes, and glycogen and secretory granules. Fewer than 1% of cultured epithelial cells differentiated into enteroendocrine cells. Active proliferation of the epithelial cells and many apoptotic cells in the inner lumen revealed the rapid cell turnover in gastrospheres in vitro. This method enables us to investigate the role of signaling between cell-cell and epithelial-mesenchymal interactions in an environment that is extremely similar to the in vivo environment.

Telmisartan Inhibits Cell Proliferation by Blocking Nuclear Translocation of ProHB-EGF C-Terminal Fragment in Colon Cancer Cells

Background & Aims Current treatment target toward advanced colorectal cancers is mainly focused on the epidermal growth factor receptor (EGFR) signaling, but its additive effects with chemotherapy are still limited. A disintegrin and metalloproteinase (ADAM) cleaves the proheparin-binding epidermal growth factor like growth factor (proHB-EGF). And soluble HB-EGF activates EGFR. In parallel, the carboxy-terminal fragment of proHB-EGF (HB-EGF-CTF) translocates into the inner nuclear membrane, and subsequently exerts on the regulation of cell proliferation by binding nuclear promyelocytic leukemia zinc finger (PLZF) protein, a transcriptional repressor, thereby causing its nuclear export. We hypothesized that the inhibition of HB-EGF-CTF nuclear translocation may be a new strategy in preventing cell proliferation. Methods 12-O-tetradecanoylphorbor-13-acetate (TPA) was treated to activate ADAM. Nine-thousand chemical compounds were screened for their efficacies in blocking the binding of HB-EGF-CTF to promyelocytic leukemia zinc finger (PLZF) with Alphascreen system. The obtained candidates were then used to block the binding of HB-EGF-CTF to PLZF in colon cancer cells, HT29 and HCT116. Cell proliferation was investigated with a growth curve assay. The intracellular localization, and association between HB-EGF-CTF and PLZF, was assessed with immunofluorescent staining, and immunoprecipitation and Western blotting, respectively. The effects of obtained candidates on EGFR phosphorylation and on nuclear translocation of HB-EGF-CTF and export of PLZF during the angiotensin II type1 receptor (AT1R) knockdown were also investigated. Results Telmisartan and candesartan were found to be potential candidates. Telmisartan inhibited TPA-induced cell proliferation stronger than candesartan. Telmisartan, but not candesartan blocked the nuclear translocation of HB-EGF-CTF, and binding of HB-EGF-CTF to PLZF, during TPA stimulation. Both telmisartan and candesartan did not inhibit TPA-induced EGFR phosphorylation, and telmisartan, but not candesartan, inhibited TPA-induced nuclear translocation of HB-EGF-CTF after knockdown of AT1R. Conclusions The inhibition of HB-EGF-CTF nuclear translocation with telmisartan may be a novel strategy in preventing cell proliferation.

Annexin A2 regulates a disintegrin and metalloproteinase 17-mediated ectodomain shedding of pro-tumor necrosis factor-α in monocytes and colon epithelial cells.

Background:Understanding the mechanism of tumor necrosis factor (TNF)-&agr; shedding is important because TNF-&agr; triggers inflammatory bowel disease development. A disintegrin and metalloproteinase (ADAM) 17 is a key enzyme for the shedding of not only the type 1 membrane-anchored protein, amphiregulin, but also the type 2 protein, TNF-&agr;. However, the detailed mechanism by which ADAM17 cleaves type 1 and 2 membrane-anchored proteins is unclear. Annexin (ANX) A2 is involved in ADAM17-mediated amphiregulin shedding. In this study, we examined whether ANX A2 is involved in TNF-&agr; shedding. Methods:We prepared U937, HT29, and HCT116 cells overexpressing alkaline phosphatase (AP)-tagged proTNF-&agr; and depleted ADAM17 and ANX A2. We assessed TNF-&agr; release and shedding by measuring the TNF-&agr; release concentration and AP activities in conditioned media after interleukin-1&bgr; or 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulation by enzyme-linked immunosorbent assay and AP assay, respectively. A direct association of ANX A2 with ADAM17 was examined with immunoprecipitation and Western blotting. Results:Enzyme-linked immunosorbent assay and AP assay showed interleukin-1&bgr;–induced TNF-&agr; shedding in HCT116 and HT29 cells and TPA-induced TNF-&agr; release in U937 cells. KB-R7785 and ADAM17 depletion significantly blocked TNF-&agr; shedding by TPA. ANX A2 depletion significantly inhibited TNF-&agr; shedding by interleukin-1&bgr; and TPA. In contrast, ANX A2 depletion did not abrogate ADAM17-mediated amphiregulin and heparin-binding epidermal growth factor-like growth factor shedding. ANX A2 was directly associated with ADAM17. Conclusions:ANX A2 was closely associated with ADAM17 and played an important role in TNF-&agr; shedding by TPA. Inhibition of ANX A2 might be a new therapeutic strategy for prevention of TNF-&agr; shedding during inflammatory bowel disease inflammation.

Infliximab salvage therapy for patients with ulcerative colitis who failed to respond to tacrolimus.

Objective Infliximab and tacrolimus are effective for the treatment of patients with moderate or severe corticosteroid-dependent/refractory ulcerative colitis. However, regarding treatment for these patients, whether tacrolimus therapy should precede infliximab as a second-line therapy remains controversial. To address this issue, we retrospectively investigated the efficacy of infliximab salvage therapy for patients with severe or moderate ulcerative colitis who failed to respond to tacrolimus. Methods We assessed clinical backgrounds and therapeutic outcomes at baseline, 8, and 30 weeks for 13 patients receiving infliximab for severe or moderate ulcerative colitis who showed refractoriness or loss of response to tacrolimus, or no tolerance. Results Mean partial Mayo score was significantly decreased (P<0.05) to 5.69, 3.07, and 2.77 at baseline, 8, and 30 weeks, respectively. Six of 13 patients (46.2%) showed clinical remission at 8 weeks and four (30.8%) showed clinical remission at 30 weeks. Two patients who did not respond to infliximab finally underwent colectomy. Rates of clinical remission at 8 and 30 weeks were 60.0 and 40.0% in tacrolimus responders, and good remission rates of 37.5 and 25.0%, respectively, were also obtained in tacrolimus nonresponders. No serious adverse events were encountered. Conclusion Infliximab salvage therapy following tacrolimus tended to appear more efficacious in tacrolimus responders (loss of response or no tolerance) than in nonresponders (refractoriness), although nonresponders also achieved satisfactory results. Sequential therapy may thus prove useful and well tolerated. In addition, we should avoid missing the proper timing of colectomy, and care is warranted regarding adverse events.

Colon Mucosa Exhibits Loss of Ectopic MUC5AC Expression in Patients with Ulcerative Colitis Treated with Oral Tacrolimus

Background. Tacrolimus (FK506) is effective for patients with ulcerative colitis (UC). However, there are few reports on tacrolimus therapy (TT) with respect to the relationship with endoscopic and clinicopathologic findings. Methods. Thirty patients with moderate/severe active UC refractory to or dependent on corticosteroid were treated with oral tacrolimus. The expression of ectopic MUC5AC in the colon was pathologically analyzed before and at 12 weeks after TT, evaluating the Mayo score and steroid-sparing effects. Results. Both mean disease and endoscopic activity index scores were reduced at levels of statistical significance in 26 UC patients receiving more than one month of TT (P < 0.0001). The dose of prednisolone was reduced by a statistically significant amount (P = 0.00022), and 14 of the 26 patients (53.8%) had steroid-free status 12 weeks after TT. The decrease in ectopic MUC5AC expression in the mucous cells of the colon was significantly associated with endoscopic improvement of inflammation in the UC patients with TT (P = 0.043). Loss of ectopic MUC5AC expression was detected in all patients who had complete response. Conclusions. Tacrolimus appears to be effective for the treatment of moderate/severe UC patients. Loss of ectopic MUC5AC expression may be important for pathologic remission in the colon of UC patients.

Therapeutic Effects of Biobran, Modified Arabinoxylan Rice Bran, in Improving Symptoms of Diarrhea Predominant or Mixed Type Irritable Bowel Syndrome: A Pilot, Randomized Controlled Study

Background. Recently, it was revealed that low grade mucosal inflammation and/or immune imbalance of the lower digestive tract is one of the mechanisms involved in symptom generation in patients with irritable bowel syndrome (IBS). Biobran, arabinoxylan compound derived from rice bran, has been reported to have several biological actions such as anti-inflammatory and immune modulatory effects. So we investigated the therapeutic effects of Biobran in patients with IBS. Method. Forty patients with diarrhea predominant or mixed type IBS were randomly assigned to either a Biobran group for treatment with Biobran or a placebo group. Therapeutic efficacy and IBS symptoms were assessed subjectively by the patients after 4 weeks of administration. Results. The global assessment was effective in 63.2% of the Biobran group and in 30% of the placebo group (P < 0.05, Biobran group versus placebo group). Biobran group showed a significant decrease in the score of diarrhea and constipation and in CRP value. However, no significant changes were observed in the placebo group. Conclusion. The administration of Biobran improved IBS symptoms. It is likely that anti-inflammatory and/or immune modulatory effects of Biobran might be useful in IBS patients.

Combination Therapy with Intensive Granulocyte and Monocyte Adsorptive Apheresis plus Adalimumab: Therapeutic Outcomes in 5 Cases with Refractory Crohn's Disease

Adalimumab (ADA) is applied to induce remission in patients with Crohn’s disease (CD) naïve to chimeric anti-tumor necrosis factor-α (anti-TNF-α), infliximab or patients with loss of response to scheduled maintenance infliximab. Adsorptive granulocyte and monocyte apheresis (GMA) depletes elevated/activated myeloid lineage leucocytes as sources of inflammatory cytokines and has been used to treat patients with CD. This study was to investigate the efficacy of intensive GMA in combination with ADA as remission induction therapy in cases of CD refractory to medications including anti-TNF-α therapies. Between December 2010 and February 2012, 5 consecutive cases with refractory CD were treated with intensive GMA (2 sessions per week) plus ADA to induce remission. CD activity index (CDAI), C-reactive protein (CRP), and endoscopic findings based on the simple endoscopic score for CD (SES-CD) at baseline and 10 weeks post 5 ADA injections were applied to determine treatment efficacy outcomes. At week 10 post ADA treatment, clinical remission together with normal CRP levels were achieved in all 5 cases, while SES-CD scores reflected marked improvement in 3 cases and partial improvement in 2 cases who had extensive deep longitudinal CD lesions. The CDAI and CRP values at baseline were 324 ± 118 and 4.9 ± 3.3 mg/dl, respectively. The corresponding values after treatment were 100 ± 28 (p = 0.024) and 0.2 ± 0.2 mg/dl (p = 0.038). In these 5 cases with medication-refractory CD, combination therapy with intensive GMA followed by 5 ADA shots appeared to be an effective and safe intervention for inducing clinical remission.

Management of systolic blood pressure after endoscopic submucosal dissection is crucial for prevention of post-ESD gastric bleeding.

Objective Endoscopic submucosal dissection (ESD) is a useful technique for early gastric neoplasms without lymph node metastasis. However, a critical complication is unpredictable post-ESD bleeding. Some risk factors for post-ESD bleeding have been reported previously, although those risk factors have not directly contributed toward prevention of post-ESD bleeding. Materials and methods We retrospectively identified 186 gastric neoplasms in 183 consecutive patients treated with ESD from 2005 to 2012 at Nagoya City University Hospital, and divided them into two groups on the basis of the presence or absence of post-ESD bleeding. Results Of the 186 lesions, eight lesions (4.2%) developed post-ESD bleeding. Univariate analysis identified hypertension (38.8% in nonbleeding vs. 87.5% in bleeding; P=0.009) and depressed-type tumors (26.4% in nonbleeding vs. 62.5% in bleeding; P=0.040) as significantly related to the incidence of post-ESD bleeding. On multivariate analysis, hypertension (odds ratio, 11.55; 95% confidence interval, 1.20–111.66; P=0.034) and depressed-type tumors (odds ratio, 5.36; 95% confidence interval, 1.12–25.73; P=0.036) were independent risk factors for post-ESD bleeding. Systolic blood pressure (SBP) after ESD was significantly higher in the post-ESD bleeding group than in the post-ESD non-bleeding group (P=0.021), with the comorbidity of hypertension significantly correlating with SBP after ESD (&rgr;=0.332, P<0.001). Conclusion Control of SBP after ESD is important for the prevention of post-ESD bleeding because hypertension as a comorbidity, which is associated positively with SBP after ESD, is a significant risk factor for post-ESD bleeding.

Long-Term Efficacy of Adalimumab in Patients With Intestinal Behcet’s Disease: Eight Consecutive Cases

The long-term efficacy and safety of adalimumab (ADA) for the treatment of intestinal Behcet’s disease (BD) in the clinical setting have not been evaluated previously. This retrospective study evaluated the 52-week efficacy of ADA in BD patients. A total of eight patients who were refractory to conventional therapy were given ADA (160/80/40 mg every other week). Marked improvement (MI) was achieved by 10 weeks in five patients (62.5%), and by 52 weeks in six patients (75%). In addition, complete remission was obtained in two patients (25%) at both 10 and 52 weeks. Improvement of global gastrointestinal (GI) symptoms to score 0 was observed in three patients (37.5%) at 10 weeks and four patients (50%) at 52 weeks. Moreover, improvement of endoscopic assessment to score 0 was also seen in four patients (50%) at both 10 and 52 weeks. No adverse events were observed in any patients during the 52 weeks. In conclusion, ADA offers an effective, well-tolerated treatment for intestinal BD in patients who are refractory to conventional therapy.