Abstract

Differentiation Factors as Tumor Suppressors: Notch/Atoh1 Pathway in Colon Cancer

Noah F. Shroyer

Loss of cellular differentiation is one of the hallmarks of cancer; in colorectal cancer (CRC), a reduction in mucin producing goblet cells is frequently observed. We have previously identified the transcription factor ATOH1 as a critical gatekeeper for the program of Notch-directed intestinal epithelial differentiation. In this model, Notch and ATOH1 activities counterbalance to select absorptive (colonocyte) or secretory (goblet, enteroendocrine) cell fates. We found that ATOH1 is silenced in ~80% of human CRCs, by both CpG island methylation and genomic microdeletion. In several mouse CRC models, mutation of Atoh1 enhances CRC tumorigenesis. Other investigators found that Notch activity is high in human CRCs, where it promotes tumorigenesis. Inhibiting Notch activity with γ-secretase inhibitors (GSI) increased ATOH1 and goblet cell production and reduced proliferation. However, Atoh1-mutant tumors showed no response when treated with GSI. ATOH1-regulated genes include transcription factors such as SPDEF, which controls terminal differentiation of goblet cells. SPDEF is coordinately silenced with ATOH1 in CRC. Furthermore, SPDEF functions as a tumor suppressor in mouse models of CRC, where loss of SPDEF increases tumor burden, while its re-expression prevents tumor growth. Our results suggest that Notch exerts its effects on CRCs coordinately with ATOH1. In most human CRCs, silencing of ATOH1 promotes tumorigenesis and will prevent a chemotherapeutic response to Notch inhibitors. Therapeutic targeting of factors downstream of ATOH1 such as SPDEF may succeed in tumors that have silenced ATOH1. This work supports the concept of using differentiation factors as targets for cancer treatment.

Emerging Medical Therapies for the Irritable Bowel Syndrome

William D. Chey

The Irritable Bowel Syndrome (IBS) is a prevalent symptom-based disorder defined by the presence of abdominal pain and altered bowel habits. Clinical phenotypes of IBS are quite diverse with some patients reporting constipation (IBS-C), others diarrhea (IBS-D) and the balance, a mixture of both. Similarly, the pathogenesis of IBS is diverse. IBS is not a single disease entity but rather, likely comprised of a number of different disease states. This fact has important implications for the choices and efficacy of treatments for IBS. Traditional therapies such as fiber, anti-diarrheals, laxatives and anti-spasmodicsprovide limited benefit to the breadth of symptoms experienced byIBS patients. Recent drug development has attempted to leverage our increasing understanding of the pathogenesis of IBS and in so doing, more comprehensively address the full spectrum of IBS symptoms. Drugs such as alosetron, ramosetron, tegaserod, and lubiprostone represent the initial attempts of such efforts. Promising drugs in development for IBS-C include other 5-HT4 receptor agonists like prucalopride, guanylatecyclase C agonists including linaclotide and plecanatide, and drugs which affect colonic bile acid concentrations such as A3309. For patients with IBS-D, drugs and supplements which alter the gut microbiome and immune function such as the nonabsorbable antibiotic rifaximin or various probiotics have been evaluated. Drugs which act on targets along the brain-gut axis such as the κ-opioid receptor agonist asimadoline, CRF-1R antagonists, the 2,3-benzodiazepine modulator dextifisopam, or the TPH-1 inhibitor LX1031 are in various stages of development. More peripherally acting drugs such as the carbon based adsorbent AST100 or drugs which inhibit intestinal chloride secretion such as crofelemer have also been studied.

Autoantibodies in Scurfy Mice and IPEX Patients Recognize Keratin 14

Eva N. Hadaschik, Troy Torgersson, Deborah D. Glass and Ethan E. Shevach

For many autoimmune disorders the nature of the antigenic targets are unknown. The Scurfy mouse spontaneously develops autoimmune disease due to a loss-of-function mutation in the foxp3 gene, a transcription factor important for the development and function of regulatory T cells. The skin is one of the main organs affected in Scurfy mice and we have previously shown, that several keratins, including keratin 14, are targets for autoreactive B cells in the skin. Patients with the rare “Immunodysregulation, Polyendocrinopathy, Enteropathy, X-linked syndrome” (IPEX) suffer from generalized autoimmunity due to the same mutation in the FOXP3 gene and often present with severe atopic-dermatitis-like skin disease. We evaluated the keratin 14-reactivity in IPEX patients with or without skin disease. We used sera from IPEX patients for western blot analysis: Two patient sera showed reactivity to keratinocyte extract, and interestingly one of the patients with skin disease yielded the strongest signal. We used the serum of this patient for a 2D-gel electrophoresis followed by Protein Identification and identified keratin 14, keratin 10 and keratin 1 as targets recognized by the autoantibodies. To conclusively demonstrate that the autoantibodies target keratin 14, we expressed 3 protein fragments covering the whole keratin 14 protein and used them for western blot analysis with the IPEX patient serum. As in Scurfy mice, the C-terminal fragment of keratin-14 was predominantly recognized by the patient serum. In summary we show that autoantibodies from IPEX patients recognize different keratins including keratin 14 and conclude that keratin 14 is an antigenic target in autoimmune skin disease in IPEX patients.

p53 Mutation and TGFβ Signaling Culminate in Cancer Invasiveness via GEP100-arf6-aMAP1 Pathway

Hisataka Sabe, Ari Hashimoto, Ayumu Yoshikawa, Hirokazu Sugino, Yutaro Otsuka, Haruka Handa, Shizuka Mito, Hiroki Sato, Jin-Min Nam, Yasuhito Onodera and Shigeru Hashimoto

Mutation of p53 tumor suppressor protein is very frequent in cancer, and often gains oncogenic activities, rather than simply abrogating its tumor suppressive functions. Identification of genes whose expression is altered as a result of p53 mutation and hence elicit tumor malignancy is the major goal of current cancer research. This may be a difficult task, however, because like wt p53 cellular functions of oncogenic p53s appear to be highly contextual, and the final readouts of the mutant p53s may not be simply determined only by biochemical properties by their own. On the other hand, another aspect towards the substantial understanding of mutant p53-driven cancer malignancy would be to identify molecular machineries that actually accomplish invasive and metastatic phenotypes in response to mutant p53s. TGFβ1 is produced mostly upon inflammation and wounding. Among different signaling pathways, TGFβ signaling was found to be most frequent in inducing invasive and mesenchymal properties, as well as generating cancer stem cell-like cell properties of human primary breast cancers. A series of our studies have shown that GEP100-Arf6-AMAP1 signaling pathway is frequently upregulated in many breast cancers and contributes to invasiveness and cancerous EMT, by promoting the recycling of β1 integrins, such as α3β1, and the downregulation of E-cadherin. Here, we describe this signaling pathway, as well as detailed mechanisms by which it works in invasion and metastasis. We also show that TGFβ1 signaling activates this GEP100-Arf6-AMAP1 pathway, and provide lines of evidence that mutant p53s, like R280?K, are essential for this activation.

Sports Injury Surveillance Study and Injury Prevention in Japan
- Focusing the ACL Injury Prevention -

Toru Fukubayashi

Recently sports medicine has the certain trend from the treatment of injured athletes to the injury prevention. Injury surveillance study is the first step for the injury prevention. Japan Amateur Sports Association (JASA) started injury surveillance study project from two years ago. The data of the National Agency for the Advancement of Sports and Health (NAASH) showed the high incidence rate of the anterior cruciate ligament (ACL) injury in female senior high school basketball payers. Most of these cases were non contact injuries. From the Model-Based Image Matching (MBIM) method by Koga et al., the injury mechanism becomes obvious. It is due to the valgus internal rotation of the knee at the time of landing and turning. There are several world famous ACL injury prevention programs, in which not only the muscle training but also the core balance training is emphasized to prevent the valgus knee position. For the female basketball players we made a special prevention program in 2007. We also applied the FIFA11+ program for the collage football players and junior female football players for these several years. We would like to talk about the result of these clinical applications.