Data from NF-κB–Dependent Plasticity of the Epithelial to Mesenchymal Transition Induced by <i>Von Hippel-Lindau</i> Inactivation in Renal Cell Carcinomas

Abstract

&lt;div&gt;Abstract&lt;p&gt;The critical downstream signaling consequences contributing to renal cancer as a result of loss of the tumor suppressor gene &lt;i&gt;von Hippel-Lindau&lt;/i&gt; (&lt;i&gt;VHL&lt;/i&gt;) have yet to be fully elucidated. Here, we report that &lt;i&gt;VHL&lt;/i&gt; loss results in an epithelial to mesenchymal transition (EMT). In studies of paired isogenic cell lines, &lt;i&gt;VHL&lt;/i&gt; silencing increased the levels of N-cadherin and vimentin and reduced the levels of E-cadherin relative to the parental VHL&lt;sup&gt;+&lt;/sup&gt; cell line, which displayed the opposite profile. VHL&lt;sup&gt;+&lt;/sup&gt; cells grew as clusters of cuboidal and rhomboid cells, whereas VHL-silenced cells took on an elongated, fibroblastoid morphology associated with a more highly invasive character in Matrigel chamber assays. Based on earlier evidence that &lt;i&gt;VHL&lt;/i&gt; loss can activate NF-κB, a known mediator of EMT, we tested whether NF-κB contributed to VHL-mediated effects on EMT. On pharmacologic or molecular inhibition of NF-κB, VHL-silenced cells regained expression of E-cadherin, lost expression of N-cadherin, and reversed their highly invasive phenotype. Introducing a pVHL-resistant hypoxia-inducible factor 1α (HIF1α) mutant (HIFα&lt;sup&gt;M&lt;/sup&gt;) into VHL&lt;sup&gt;+&lt;/sup&gt; cells heightened NF-κB activity, phenocopying EMT effects produced by VHL silencing. Conversely, inhibiting the heightened NF-κB activity in this setting reversed the EMT phenotype. Taken together, these results suggest that &lt;i&gt;VHL&lt;/i&gt; loss induces an EMT that is largely dependent on HIFα-induced NF-κB. Our findings rationalize targeting the NF-κB pathway as a therapeutic strategy to treat renal tumors characterized by biallelic &lt;i&gt;VHL&lt;/i&gt; inactivation. Cancer Res; 70(2); 752–61&lt;/p&gt;&lt;/div&gt;