Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer in the United States, affecting one million people per year. Patients with aggressive disease have limited treatment options and high mortality, highlighting the need to identify new biomarkers linked to poor clinical outcome. HRAS mutations are found in skin papillomas and cSCCs and increase in frequency when MAP3K family members are inhibited, suggesting a link between blockade of mitogen-activated protein kinase (MAPK) signaling and initiation of RAS-primed cells. Tpl2, a MAP3K gene, can serve as a tumor suppressor gene in cSCC. We have previously shown that upon Tpl2 ablation, mice have heightened sensitivity to aberrant RAS signaling. Tpl2-/- mice display significantly higher numbers of papillomas and cSCCs in two-stage chemical carcinogenesis studies and increased tumorigenicity of keratinocytes expressing oncogenic v-rasHa in nude mouse skin grafts. In part, this is mediated through increased mesenchymal-epithelial transition factor (MET) receptor activity. Epidermal Growth Factor Receptor (EGFR) is reported to be an essential factor for MET-driven carcinogenesis and MET activation may confer resistance to EGFR therapies, suggesting that the concurrent use of both an EGFR inhibitor and a MET inhibitor may show promise in advanced cSCCs. In this study we assessed whether normal or Ras-transformed Tpl2-/- keratinocytes have aberrant EGFR signaling and whether concomitant treatment with EGFR/MET tyrosine kinase inhibitors was more effective than single agents in reducing growth and angiogenic potential of Ras-transformed keratinocytes. Tpl2-/- keratinocytes exhibited increased HER-2 and STAT-3 under basal conditions and elevated p-MET and p-EGFR when transduced with oncogenic RAS. Inhibition of MET by Capmatinib increased p-EGFR in Tpl2-/- keratinocytes and papillomas, and inhibition of EGFR by Gefitinib increased HER2 and HER3 signaling in both genotypes. Treatment of keratinocytes with EGFR and MET inhibitors, in combination, significantly enhanced endothelial tube formation, MMP-9 activity and activation of other RTKs, with more pronounced effects when Tpl2 was ablated. These data indicate that Tpl2 cross-talks with both EGFR and MET signaling pathways. Upon inhibition of EGFR/MET signaling, a myriad of escape mechanisms exists in keratinocytes to overcome targeted drug effects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.