E-cadherin is a calcium-dependent transmembrane molecule that mediates homophilic interactions that are critical in mediating cell adhesion. Disruption of E-cadherin function is a hallmark feature of esophageal cancer (a common cancer in the US and worldwide), and other epithelial cancers. This leads to the promotion of esophageal cancer cell migration and invasion. Our preliminary data reveal that overexpression of E-cadherin upregulates TGFb receptor II (TGFRII) and statistically significant coordinated loss of both in esophageal cancer tissues. We have used primary human esophageal epithelial cells to analyze the loss of E-cadherin by retrovirally introducing a dominant-negative mutant version of E-cadherin lacking the cytoplasmic tail resulting in augmented cell migration and invasion. Thus, our overall hypothesis is that there is functional interplay between E-cadherin and TGFRII in esophageal cancer cell migration, invasion and EMT. We will test our hypothesis by pursiung [sic] the following interrelated Specific Aims.
Specific Aim 1 : A. To identify the domain(s) mediating the physical interaction between E-cadherin and TGFRII. We will generate deletion mutants of TGFRII and E-cadherin and map the specific domains necessary for interaction in vitro and in vivo. B. To analyze the mechanistic effects on cell migration and invasion mediated by the TGFRII / E- cadherin interaction. We will use the above mentioned mutants and a dominant-negative mutant of TGFRII to test how the normal interaction and loss of interaction influences cell migration, invasion and EMT.
Specific Aim 2 : To determine how E-cadherin stabilizes TGFRII and regulates its degradation and function. We will analyze the effects of E-cadherin on TGFRII expression and determine the kinetics of TGFRII degradation by analyzing TGFRII association with the endosome or proteasome machinery.
Specific Aim 3 : To analyze the effects of loss of E-cadherin function in vivo using mouse models. We will use mouse models to investigate the loss of E-cadherin in the esophagus and how this pertains to the regulation of TGFRII function and the induction of tumorigenesis. In addition, new mouse models will be established using dominant-negative E-cadherin to directly model and recapitulate our in vitro findings. In aggregate, these studies will provide insights into the importance of E-cadherin and TGFRII to mediate esophageal cancer cell migration and invasion, hopefully translating into novel approaches for therapeutics.
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