Activin A-mediated epithelial de-differentiation contributes to injury repair in an in vitro gastrointestinal reflux model

Reflux esophagitis is a result of esophageal exposure to acid and bile during episodes of gastroesophageal reflux. Aside from chemical injury to the esophageal epithelium, it has been shown that acid and bile induce cytokine-mediated injury by stimulating the release of pro-inflammatory cytokines. During the repair and healing process following reflux injury, the squamous esophageal cells are replaced with a columnar epithelium causing Barrett's metaplasia, which predisposes patients to esophageal adenocarcinoma. We identified a novel player in gastroesophageal reflux injury, the TGFβ family member Activin A (ActA), which is a known regulator of inflammation and tissue repair. In this study, we show that in response to bile salt and acidified media (pH 4) exposure, emulating the milieu to which the distal esophagus is exposed during gastroesophageal reflux, long-term treated, tolerant esophageal keratinocytes exhibit increased ActA secretion and a pro-inflammatory cytokine signature. Furthermore, we noted increased motility and expression of the stem cell markers SOX9, LGR5 and DCLK1 supporting the notion that repair mechanisms were activated in the bile salt/acid-tolerant keratinocytes. Additionally, these experiments demonstrated that de-differentiation as characterized by the induction of YAP1, FOXO3 and KRT17 was altered by ActA/TGFβ signaling. Collectively, our results suggest a pivotal role for ActA in the inflammatory GERD environment by modulating esophageal tissue repair and de-differentiation.

Esophageal cancer: The latest on chemoprevention and state of the art therapies

Esophageal cancer is currently the 8th most common cancer worldwide and the 6th leading cause of cancer-related mortality. Despite remarkable advances, the mortality for those suffering from esophageal cancer remains high, with 5-year survival rates of less than 20%. In part, because most patients present with late-stage disease, long-term survival even after resection and therapy is disappointingly low. As we will discuss in this review, multiple characteristics specific to the disease stage and patient must be considered when choosing a treatment plan. This article will summarize current standard therapies, potential application of chemoprevention drugs and the promise and partial failure of personalized medicine, as well as novel treatments addressing this disease.

Abstract 335: A genetic mouse model of head-and-neck squamous cell carcinoma using targeted deletion of E-cadherin and TGFβ receptor II

We previously observed that 70% of esophageal tumors demonstrated coordinated loss of E-cadherin and TGFβRII. When grown in three-dimensional organotypic reconstruct cultures, cells lacking E-cadherin and TGFβRII demonstrate fibroblast-dependent invasion into the underlying matrix. Therefore, we hypothesized that coordinated loss of CDH1 (E-cadherin) and TGFBR2 (TGFβRII) will induce tumorigenesis in vivo. We developed a mouse model targeting CDH1 and TGFBR2 loss in the oral-esophageal epithelium using the Epstein-Barr virus L2 promoter, ED-L2. For spatio-temporal control of CDH1- and TGFBR2 gene expression, we also generated an inducible mouse model using Cre-ERT(tam) under the control of the keratin 14 promoter. Few mouse models focusing on genetic alterations of oral and head-and-neck cancer exist. We show that the loss of E-cadherin and TGFβ receptor II without carcinogen treatment is sufficient to induce invasive HNSCC and forestomach tumors. Double knock-out animals succumb to the disease between 1 and 1.5 years of age and show invasive tumors in the oral cavity and tongue, as well as the forestomach. Advanced tumors metastasize to the lung. The tumors are characterized by Ki67-positive and p63-positive staining and show disruption of adherens junctions with loss of β-catenin and mislocalisation of p120 to the cytoplasm. Additional genetic modifications frequently described for HNSCC are the upregulation of c-myc and cyclin D1. We could show that the oral mouse tumors are positive for these markers allowing us to conclude that this animal model recapitulates HNSCC at the pathologic and molecular levels. Furthermore, the forestomach is an extension of the squamous epithelium of the esophagus in the mouse. Known genetic alterations causing esophageal squamous cancer are amplification of EGFR, cyclin D1 and mutations in p53 in addition to the loss of E-cadherin and TGFβRII. The analysis of the forestomach tumors recapitulates these events in the mouse model as a result of CDH1 and TGFBR2 loss. This tumor model will provide us with a unique tool for testing therapeutic approaches.

Citation Format: Thomas Andl, Gregoire F. Le Bras, Nicole F. Richards, Gillian L. Allison, M. Kay Washington, R. Katie Lee, Claudia D. Andl. A genetic mouse model of head-and-neck squamous cell carcinoma using targeted deletion of E-cadherin and TGFβ receptor II. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 335. doi:10.1158/1538-7445.AM2013-335