Hironobu Tsukamoto

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.

TGFβ induces proHB-EGF shedding and EGFR transactivation through ADAM activation in gastric cancer cells

BACKGROUND AND AIMS Transforming growth factor-beta (TGFβ) is known to potently inhibit cell growth. Loss of responsiveness to TGFβ inhibition on cell growth is a hallmark of many types of cancer, yet its mechanism is not fully understood. Membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF) ectodomain is cleaved by a disintegrin and metalloproteinase (ADAM) members and is implicated in epidermal growth factor receptor (EGFR) transactivation. Recently, nuclear translocation of the C-terminal fragment (CTF) of pro-HB-EGF was found to induce cell growth. We investigated the association between TGFβ and HB-EGF signal transduction via ADAM activation. MATERIALS AND METHODS The CCK-8 assay in two gastric cancer cell lines was used to determine the effect for cell growth by TGFβ. The effect of two ADAM inhibitors was also evaluated. Induction of EGFR phosphorylation by TGFβ was analyzed and the effect of the ADAM inhibitors was also examined. Nuclear translocation of HB-EGF-CTF by shedding through ADAM activated by TGFβ was also analyzed. EGFR transactivation, HB-EGF-CTF nuclear translocation, and cell growth were examined under the condition of ADAM17 knockdown. RESULT TGFβ-induced EGFR phosphorylation of which ADAM inhibitors were able to inhibit. TGFβ induced shedding of proHB-EGF allowing HB-EGF-CTF to translocate to the nucleus. ADAM inhibitors blocked this nuclear translocation. TGFβ enhanced gastric cancer cell growth and ADAM inhibitors suppressed this effect. EGFR phosphorylation, HB-EGF-CTF nuclear translocation, and cell growth were suppressed in ADAM17 knockdown cells. CONCLUSION HB-EGF-CTF nuclear translocation and EGFR transactivation from proHB-EGF shedding mediated by ADAM17 activated by TGFβ might be an important pathway of gastric cancer cell proliferation by TGFβ.

Multicenter, prospective trial of white-light imaging alone versus white-light imaging followed by magnifying endoscopy with narrow-band imaging for the real-time imaging and diagnosis of invasion depth in superficial esophageal squamous cell carcinoma.

BACKGROUND Magnifying endoscopy with narrow-band imaging (ME-NBI) has been used to estimate the invasion depth of superficial esophageal squamous cell carcinoma (SESCC), but the real diagnostic power of ME-NBI remains unclear because of few prospective studies. OBJECTIVES To evaluate whether ME-NBI adds additional information to white-light imaging (WLI) for the diagnosis of invasion depth of SESCC. DESIGN Multicenter, prospective trial using real-time imaging and diagnosis. SETTING Seven Japanese institutions. PATIENTS Fifty-five patients with SESCC were enrolled from June 2011 to October 2013, and the results for 49 lesions were analyzed. INTERVENTIONS Patients underwent primary WLI followed by ME-NBI, and reports of primary WLI (WLI alone) were completed before secondary ME-NBI (WLI followed by ME-NBI). To standardize diagnosis among examiners, this trial was started after achievement of a mean κ value≥.6 among 11 participating endoscopists. MAIN OUTCOME MEASUREMENTS Diagnosis of invasion depth by each tool was divided into cancer limited to the epithelium and the lamina propria mucosa and cancer invading beyond the muscularis mucosae (≥T1a-MM) and then collated with the final pathologic diagnosis by an independent pathologist blinded to the clinical data. RESULTS The accuracy of invasion depth in WLI alone and WLI followed by ME-NBI was 71.4% and 65.3% (P=.375), respectively. Sensitivity for ≥T1a-MM was 61.1% for both groups (P=1.000), and specificity for ≥T1a-MM was 77.4% for WLI alone and 67.7% for WLI followed by ME-NBI (P=.375). LIMITATION Open-label trial. CONCLUSIONS ME-NBI showed no additional benefit to WLI for diagnosis of invasion depth of SESCC. (University Hospital Network Clinical Trials Registry number: UMIN000005632.).

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.