Inhibition of BMP2 and BMP4 Represses Barrett's Esophagus While Enhancing the Regeneration of Squamous Epithelium in Preclinical Models.

BACKGROUND & AIMS: Barrett's esophagus is considered to be a metaplastic lesion that predisposes for esophageal adenocarcinoma. Development of Barrett's esophagus is considered to be driven by sonic hedgehog mediated bone morphogenetic protein (BMP) signaling. We aimed to investigate in preclinical in vivo models whether targeting canonical BMP signaling could be an effective treatment for Barrett's esophagus. METHODS AND RESULTS: Selective inhibition of BMP2 and BMP4 within an in vivo organoid model of Barrett's esophagus inhibited development of columnar Barrett's cells, while favoring expansion of squamous cells. Silencing of noggin, a natural antagonist of BMP2, BMP4, and BMP7, in a conditional knockout mouse model induced expansion of a Barrett's-like neo-columnar epithelium from multi-lineage glands. Conversely, in this model specific inhibition of BMP2 and BMP4 led to the development of a neo-squamous lineage. In an ablation model, inhibition of BMP2 and BMP4 resulted in the regeneration of neo-squamous epithelium after the cryoablation of columnar epithelium at the squamocolumnar junction. Through lineage tracing the generation of the neo-squamous mucosa was found to originate from K5+ progenitor squamous cells. CONCLUSIONS: Here we demonstrate that specific inhibitors of BMP2 and BMP4 attenuate the development of Barrett's columnar epithelium, providing a novel potential strategy for the treatment of Barrett's esophagus and the prevention of esophageal adenocarcinoma.

Inhibition of the BMP pathway prevents development of Barrett's-associated adenocarcinoma in a surgical rat model.

INTRODUCTION: Esophageal adenocarcinoma (EAC) is an aggressive cancer, associated with reflux esophagitis and intestinal metaplasia (IM). One underlying biological mechanism, which possibly drives the development of EAC, is the dysregulated expression of Bone Morphogenetic Proteins (BMPs). AIM: To investigate if local delivery of Noggin, a BMP antagonist, reduced EAC. METHODS: After obtaining proof of principal on local delivery of a Noggin/Sucralfate substance, a randomized controlled trial to test the effects of Noggin on EAC development was performed in a surgical rat model. In the model, an esophago-jejunostomy leads to development of reflux-esophagitis, IM and eventually EAC. Rats were treated by Noggin/Sucralfate or Sucralfate alone. Treatment was administered from 26 to 29 weeks after the operation. RESULTS: Of the 112 operated rats, 52 survived beyond 26 weeks. Finally, 25 rats treated with Noggin/Sucralfate and 21 with Sucralfate, were evaluated. At the end, 39 (85%) of the animals had IM while 28 (61%) developed cancer. There were significantly more cancers in the Noggin/Sucralfate arm (50%) versus the Sucralfate group (73%) (Chi square, P < 0.05). Most cancers were mucous producing T3 adenocarcinomas. There were no significant differences in the amount of IM, size or grade of the cancers, or expression of columnar and squamous markers between the two groups. CONCLUSION: In this study, we demonstrated that inhibition of BMPs by Noggin reduced development of EAC in a surgical esophagitis-IM-EAC rat model. In future, effective targeting of the BMP pathway with selective BMP-inhibitors could become an important asset to improve EAC patient outcome.

Novel In Vivo Mouse Cryoablation Model to Explore Unique Therapeutic Approaches for Premalignant Columnar Lesions.

Patients with epithelial metaplasias have an increased risk of developing malignancies. In Barrett's esophagus, neo-columnar epithelium develops proximal to the squamous-columnar junction (SCJ) in the esophagus as the result of prolonged exposure to bile and acid reflux. Patients require lifetime periodic surveillance, due to lack of effective eradication therapies. The shortage of innovative treatment options is mostly attributable to the paucity of adequate in vivo models of neo-columnar epithelium regeneration. This protocol describes the generation of a cryoablation model to study regeneration of neo-epithelia at the SCJ. Cryoablation of the columnar and squamous mucosa at the SCJ was achieved through local application of liquid N2O in wild-type and reporter mice in combination with acid suppression. Acid suppression alone, showed restoration of the SCJ with normal histological features of both the neo-columnar and neo-squamous epithelium within 14 days. As a proof of principle, mice were treated with mNoggin, an inhibitor of bone morphogenetic proteins (BMPs), which are involved in the development of columnar epithelia. Local application of mNoggin to the ablated area at the SCJ significantly reduced the development of the neo-columnar mucosa. Although this model does not faithfully recapitulate the exact characteristics of Barrett's esophagus, it is a well-suited tool to study the mechanisms of therapeutic inhibition of neo-columnar regeneration. It therefore represents an efficient and easy platform to test novel pharmacological therapies for treatment of neo-epithelial lesions at the SCJ.

Glyco-conjugated bile acids drive the initial metaplastic gland formation from multi-layered glands through crypt-fission in a murine model.

Bile acid reflux is known to be associated with the development of Barrett's esophagus and esophageal adenocarcinoma (EAC), yet the role of specific bile acids and the mechanism behind the metaplastic changes is unclear. Here, we demonstrate that multi-layered glandular structures at the squamo-columnar junction in mice contain multiple cell lineages, which resemble the human esophageal submucosal gland ducts. Exposing mice to patient's refluxates induced expansion of multi-layered glandular structures and development of columnar metaplasia at the squamo-columnar junction. The glycine conjugated bile acids induced an intestinal type of metaplasia more typical for Barrett's esophagus. Through lineage tracing, we excluded the involvement of K5+, DCLK1+, and LGR5+ progenitor cells as the primary source in the development of the glandular metaplastic epithelium. We show that the mechanism behind development of metaplasia involves crypt fission and may be independent of stem cell proliferation. Our findings support the hypothesis that in humans, BE arises from non-squamous cells residing in submucosal gland ducts and that induction of intestinal type of metaplasia is most effectively induced by glycine-conjugated bile acids. These novel insights may lead to more effective strategies to prevent development of Barrett's esophagus and esophageal adenocarcinoma.

Dynamic clonal equilibrium and predetermined cancer risk in Barrett's oesophagus.

Surveillance of Barrett's oesophagus allows us to study the evolutionary dynamics of a human neoplasm over time. Here we use multicolour fluorescence in situ hybridization on brush cytology specimens, from two time points with a median interval of 37 months in 195 non-dysplastic Barrett's patients, and a third time point in a subset of 90 patients at a median interval of 36 months, to study clonal evolution at single-cell resolution. Baseline genetic diversity predicts progression and remains in a stable dynamic equilibrium over time. Clonal expansions are rare, being detected once every 36.8 patient years, and growing at an average rate of 1.58 cm(2) (95% CI: 0.09-4.06) per year, often involving the p16 locus. This suggests a lack of strong clonal selection in Barrett's and that the malignant potential of 'benign' Barrett's lesions is predetermined, with important implications for surveillance programs.

Increased phosphorylation on residue S795 of the retinoblastoma protein in esophageal adenocarcinoma.

Due to its increasing incidence and relatively poor prognosis, esophageal adenocarcinoma (EAC) is becoming a significant health problem. Elucidating the mechanisms underlying EAC development is of great importance to improve upon current conventional treatment strategies. Insight into phosphorylation has proven to be useful for the development of diagnostic and molecular treatment strategies in cancer. A pathway largely dependent on phosphorylation and frequently deregulated in cancer is the cell cycle regulating p16-retinoblastoma (Rb) pathway. We investigated kinase activity, specifically phosphorylation within the p16-Rb pathway, in EAC. A high-throughput peptide tyrosine kinase array containing short peptides representing 100 proteins with known phosphorylation sites, was used to assess phosphorylation activity in EAC. Also, specific phosphorylation changes of the cell cycle protein Rb and its upstream regulator P16 were validated through immunoblotting in EAC and normal esophageal cells and tissues. Phosphorylation activity was higher in EAC tissues as compared to normal squamous esophageal tissues. A majority of the proteins significantly higher phosphorylated in EAC were found to be involved in cell structure maintenance and immunity. Validation of Rb phosphorylation in EAC biopsy specimens and cell lines showed hyper phosphorylation of Rb associated with aberrant P16 expression in the cancer tissues. The specific Rb (S795) residue was significantly higher phosphorylated in EAC compared to normal esophageal tissue (Wilcoxon paired rank test, p=0.004). Investigation of Rb (S795) phosphorylation may indicate targets for intervention and give more molecular insight in EAC.

Active matrix metalloproteases are expressed early on and are high during the Barrett's esophagus malignancy sequence.

OBJECTIVE: Molecular processes underlying Barrett's malignant development are poorly understood. Matrix metalloproteases (MMPs) are enzymes involved in inflammation, tissue remodeling, and malignant development. Therefore, active MMPs may have a role in early metaplasia development and Barrett's esophagus' malignant progression. We desired to gain more insight into the role of MMPs during the Barrett's esophagus pathogenesis sequence. MATERIAL AND METHODS: In a surgical Barrett's mouse model, and in nonmalignant Barrett's and malignant esophageal cell lines, the activity of MMPs was investigated using a MMP activatable probe. MMP activity was further validated in Barrett's esophagus and esophageal adenocarcinoma patient biopsies and was further differentiated by investigating MMP9 and MMP13 expressions. RESULTS: The mouse model showed probe activation in stromal cells early on in the esophagitis and metaplasia stages. MMP probe activation was higher in the Barrett's and cancer cell lines and biopsies as compared to normal cells and tissues. Co-immunostainings confirmed that, at the tissue level, the probe activation was mostly confined to CD45-positive stromal cells. MMP13 expression was highest in Barrett's metaplasia, whereas MMP9 was highest in the esophageal adenocarcinomas. CONCLUSION: During the Barrett's pathogenesis process, MMP activity is increased early on in the inflamed esophagus and remains high in metaplasia and esophageal adenocarcinoma. However, there is a switch of MMP13 to MMP9 expression once neoplasia develops. In the future, detecting specific MMP subtypes could be used for distinguishing nonmalignant from neoplastic Barrett's esophagus.

Strategy for prevention of cancers of the esophagus.

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on the animal reflux-inflammation models for Barrett's esophagus and esophageal adenocarcinoma; genomic/epigenomic analyses; eflornithine-based combinations; the molecular derangements that promote neoplastic transformation; the role of COX-2 inhibitors, proton pump inhibitors, and phase II trials in Barrett's adenocarcinoma; statins in chemoprevention and treatment of esophageal cancer; and biomarkers as potential targets in Barrett's adenocarcinoma.

A pSMAD/CDX2 complex is essential for the intestinalization of epithelial metaplasia.

The molecular mechanisms leading to epithelial metaplasias are poorly understood. Barrett's esophagus is a premalignant metaplastic change of the esophageal epithelium into columnar epithelium, occurring in patients suffering from gastroesophageal reflux disease. Mechanisms behind the development of the intestinal subtype, which is associated with the highest cancer risk, are unclear. In humans, it has been suggested that a nonspecialized columnar metaplasia precedes the development of intestinal metaplasia. Here, we propose that a complex made up of at least two factors needs to be activated simultaneously to drive the expression of intestinal type of genes. Using unique animal models and robust in vitro assays, we show that the nonspecialized columnar metaplasia is a precursor of intestinal metaplasia and that pSMAD/CDX2 interaction is essential for the switch toward an intestinal phenotype.