Tumor Maintenance
Squamous cell carcinoma (SCC) is a notoriously treatment resistant form of cancer that can arise in many areas of the body including the skin, lungs, esophagus, digestive tract, urinary bladder, and reproductive organs. The majority of SCC tumors exhibit a dramatic increase in the expression of the p53-related transcription factor p63. Leif Ellisen and colleagues used a mouse model of SCC to demonstrate the requirement of a p63 regulated genetic program for tumor maintenance. The fibroblast growth factor receptor 2 (FGFR2) signaling pathway was identified as a target of p63 regulation. The authors demonstrate that both directed deletion of p63 and treatment with FGFR2 inhibitors within SCC tumors resulted in tumor regression. These results identify new potential therapies in the treatment of SCC. The above image shows a SCC tumor stained for transcription factor p63 (red) surrounded by activated stromal fibroblasts (stained green with smooth muscle actin).
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Abstract
Oncogenic transcription factors drive many human cancers, yet identifying and therapeutically targeting the resulting deregulated pathways has proven difficult. Squamous cell carcinoma (SCC) is a common and lethal human cancer, and relatively little progress has been made in improving outcomes for SCC due to a poor understanding of its underlying molecular pathogenesis. While SCCs typically lack somatic oncogene-activating mutations, they exhibit frequent overexpression of the p53-related transcription factor p63. We developed an in vivo murine tumor model to investigate the function and key transcriptional programs of p63 in SCC. Here, we show that established SCCs are exquisitely dependent on p63, as acute genetic ablation of p63 in advanced, invasive SCC induced rapid and dramatic apoptosis and tumor regression. In vivo genome-wide gene expression analysis identified a tumor-survival program involving p63-regulated FGFR2 signaling that was activated by ligand emanating from abundant tumor-associated stroma. Correspondingly, we demonstrate the therapeutic efficacy of extinguishing this signaling axis in endogenous SCCs using the clinical FGFR2 inhibitor AZD4547. Collectively, these results reveal an unanticipated role for p63-driven paracrine FGFR2 signaling as an addicting pathway in human cancer and suggest a new approach for the treatment of SCC.
Authors
Matthew R. Ramsey, Catherine Wilson, Benjamin Ory, S. Michael Rothenberg, William Faquin, Alea A. Mills, Leif W. Ellisen
Copyright © 2024 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)