Stromal Hedgehog signalling is downregulated in colon cancer and its restoration restrains tumour growth

A role for Hedgehog (Hh) signalling in the development of colorectal cancer (CRC) has been proposed. In CRC and other solid tumours, Hh ligands are upregulated; however, a specific Hh antagonist provided no benefit in a clinical trial. Here we use Hh reporter mice to show that downstream Hh activity is unexpectedly diminished in a mouse model of colitis-associated colon cancer, and that downstream Hh signalling is restricted to the stroma. Functionally, stroma-specific Hh activation in mice markedly reduces the tumour load and blocks progression of advanced neoplasms, partly via the modulation of BMP signalling and restriction of the colonic stem cell signature. By contrast, attenuated Hh signalling accelerates colonic tumourigenesis. In human CRC, downstream Hh activity is similarly reduced and canonical Hh signalling remains predominantly paracrine. Our results suggest that diminished downstream Hh signalling enhances CRC development, and that stromal Hh activation can act as a colonic tumour suppressor

The role of EZH2 and DNA methylation in the silencing of the tumour suppressor RUNX3 in colorectal cancer

In gastric cancer, a new epigenetic mechanism of tumour suppressor loss has been suggested where the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is responsible for loss of expression of RUNX3. This is consistent with EZH2 upregulation in multiple cancer types being associated with poor prognosis. We investigated whether EZH2 influences the expression of RUNX3 in colorectal cancer (CRC) and whether this is independent of methylation. We determined protein and messenger RNA (mRNA) levels of EZH2 and RUNX3 and assessed RUNX3 methylation with methylation-specific polymerase chain reaction using 72 human CRCs and 8 CRC cell lines. We assessed the effect of efficient RNA interference-mediated knockdown of EZH2 on RUNX3 levels, cell viability and H3K27 trimethylation of the RUNX3 promoter using chromatin immunoprecipitation. Despite higher levels of EZH2 and lower levels of RUNX3 in CRC specimens in general, no inverse correlation between EZH2 and RUNX3 in paired samples was found arguing against a major role for histone methylation in silencing RUNX3 in CRC. Conversely, downregulation of RUNX3 mRNA in the same tumours was associated with RUNX3 DNA methylation (P < 0.05). In cell lines, knockdown of EZH2 removed the repressive chromatin marks from RUNX3 but did not result in RUNX3 re-expression. However, it prevented the re-silencing of RUNX3 after the removal of demethylating agents. In conclusion, DNA methylation is primarily responsible for the transcriptional silencing of RUNX3 in CRC, but EZH2 and histone methylation are necessary for its methylation-dependent re-silencing after the removal of demethylating agents. These results would predict that inhibitors of EZH2 and histone methylation would enhance the effects of demethylating agents in cancer therapy

Epithelial calcineurin controls microbiota-dependent intestinal tumor development.

Inflammation-associated pathways are active in intestinal epithelial cells (IECs) and contribute to the pathogenesis of colorectal cancer (CRC). Calcineurin, a phosphatase required for the activation of the nuclear factor of activated T cells (NFAT) family of transcription factors, shows increased expression in CRC. We therefore investigated the role of calcineurin in intestinal tumor development. We demonstrate that calcineurin and NFAT factors are constitutively expressed by primary IECs and selectively activated in intestinal tumors as a result of impaired stratification of the tumor-associated microbiota and toll-like receptor signaling. Epithelial calcineurin supports the survival and proliferation of cancer stem cells in an NFAT-dependent manner and promotes the development of intestinal tumors in mice. Moreover, somatic mutations that have been identified in human CRC are associated with constitutive activation of calcineurin, whereas nuclear translocation of NFAT is associated with increased death from CRC. These findings highlight an epithelial cell-intrinsic pathway that integrates signals derived from the commensal microbiota to promote intestinal tumor development.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) grants ZE814/5-1 (S.Z.), BA2863/5-1 (J.F.B.) and CH279/5-1 (T.C.), the European Research Council (ERC) starting grant 336528 (S.Z.), a Postdoctoral Fellowship Award from the Crohn's and Colitis Foundation of America (S.Z.), the European Commission (Marie Curie International Reintegration grant 256363; S.Z.), the DFG Excellence Cluster 'Inflammation at Interfaces' (S.Z. and J.F.B.), the DFG Excellence Cluster 'Center for Regenerative Therapies' (S.Z.); the US National Institutes of Health grants DK044319 (R.S.B.), DK051362 (R.S.B.), DK053056 (R.S.B.) and DK088199 (R.S.B.), the Harvard Digestive Diseases Center (HDDC) grant DK0034854 (R.S.B.), and the AIRC grant IG-14233 (M.E.B.).This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nm.407

Autologous bone marrow-derived mesenchymal stromal cell treatment for refractory luminal Crohn’s disease: results of a phase I

Mesenchymal stromal cells (MSCs) are pluripotent cells that have immunosuppressive effects both in vitro and in experimental colitis. Promising results of MSC therapy have been obtained in patients with severe graft versus host disease of the gut. Our objective was to determine the safety and feasibility of autologous bone marrow derived MSC therapy in patients with refractory Crohn's disease. 10 adult patients with refractory Crohn's disease (eight females and two males) underwent bone marrow aspiration under local anaesthesia. Bone marrow MSCs were isolated and expanded ex vivo. MSCs were tested for phenotype and functionality in vitro. 9 patients received two doses of 1-2×10(6) cells/kg body weight, intravenously, 7 days apart. During follow-up, possible side effects and changes in patients' Crohn's disease activity index (CDAI) scores were monitored. Colonoscopies were performed at weeks 0 and 6, and mucosal inflammation was assessed by using the Crohn's disease endoscopic index of severity. MSCs isolated from patients with Crohn's disease showed similar morphology, phenotype and growth potential compared to MSCs from healthy donors. Importantly, immunomodulatory capacity was intact, as Crohn's disease MSCs significantly reduced peripheral blood mononuclear cell proliferation in vitro. MSC infusion was without side effects, besides a mild allergic reaction probably due to the cryopreservant DMSO in one patient. Baseline median CDAI was 326 (224-378). Three patients showed clinical response (CDAI decrease ≥70 from baseline) 6 weeks post-treatment; conversely three patients required surgery due to disease worsening. Administration of autologous bone marrow derived MSCs appears safe and feasible in the treatment of refractory Crohn's disease. No serious adverse events were detected during bone marrow harvesting and administratio

Intestinal Tumorigenesis Is Not Affected by Progesterone Signaling in Rodent Models

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the ApcMin/+ mouse, a model for spontaneous intestinal polyposis. PRKO-ApcMin/+mice exhibited no change in polyp number, size or localization compared to ApcMin/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis

Intervju: akademik Jakša Barbić

Over the past 20 years evidence has accumulated confirming the immunomodulatory role of the appendix in ulcerative colitis (UC). This led to the idea that appendectomy might alter the clinical course of established UC. The objective of this body of research is to evaluate the short-term and medium-term efficacy of appendectomy to maintain remission in patients with UC, and to establish the acceptability and cost-effectiveness of the intervention compared to standard treatment. These paired phase III multicenter prospective randomised studies will include patients over 18 years of age with an established diagnosis of ulcerative colitis and a disease relapse within 12 months prior to randomisation. Patients need to have been medically treated until complete clinical (Mayo score <3) and endoscopic (Mayo score 0 or 1) remission. Patients will then be randomised 1:1 to a control group (maintenance 5-ASA treatment, no appendectomy) or elective laparoscopic appendectomy plus maintenance treatment. The primary outcome measure is the one year cumulative UC relapse rate - defined both clinically and endoscopically as a total Mayo-score ≥5 with endoscopic subscore of 2 or 3. Secondary outcomes that will be assessed include the number of relapses per patient at 12 months, the time to first relapse, health related quality of life and treatment costs, and number of colectomies in each arm. The ACCURE and ACCURE-UK trials will provide evidence on the role and acceptability of appendectomy in the treatment of ulcerative colitis and the effects of appendectomy on the disease course. NTR2883 ; ISRCTN5652301

Hedgehog signaling in development and homeostasis of the gastrointestinal tract

The Hedgehog family of secreted morphogenetic proteins acts through a complex evolutionary conserved signaling pathway to regulate patterning events during development and in the adult organism. In this review I discuss the role of Hedgehog signaling in the development, postnatal maintenance, and carcinogenesis of the gastrointestinal tract. Three mammalian hedgehog genes, sonic hedgehog (Shh), indian hedgehog (Ihh), and desert hedgehog (Dhh) have been identified. Shh and Ihh are important endodermal signals in the endodermal-mesodermal cross-talk that patterns the developing gut tube along different axes. Mutations in Shh, Ihh, and downstream signaling molecules lead to a variety of gross malformations of the murine gastrointestinal tract including esophageal atresia, tracheoesophageal fistula, annular pancreas, midgut malrotation, and duodenal and anal atresia. These congenital malformations are also found in varying constellations in humans, suggesting a possible role for defective Hedgehog signaling in these patients. In the adult, Hedgehog signaling regulates homeostasis in several endoderm-derived epithelia, for example, the stomach, intestine, and pancreas. Finally, growth of carcinomas of the proximal gastrointestinal tract such as esophageal, gastric, biliary duct, and pancreatic cancers may depend on Hedgehog signaling offering a potential avenue for novel therapy for these aggressive cancer