ΔNp63 activates EGFR signaling to induce loss of adhesion in triple-negative basal-like breast cancer cells

• Published in: Breast cancer research and treatment Vol. 163; no. 3; pp. 475 - 484
• Main Authors: Holcakova, Jitka, Nekulova, Marta, Orzol, Paulina, Nenutil, Rudolf, Podhorec, Jan, Svoboda, Marek, Dvorakova, Petra, Pjechova, Mariana, Hernychova, Lenka, Vojtesek, Borivoj, Coates, Philip J.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-06-2017
• Subjects: Cell Adhesion - genetics; Cell Line, Tumor; Cell Proliferation - genetics; Epidermal Growth Factor - genetics; Epidermal Growth Factor - metabolism; Female; Gene Expression Regulation, Neoplastic; Humans; Medicine; Medicine & Public Health; Membrane Proteins - genetics; Neoplasm Invasiveness - genetics; Neoplasm Metastasis; Oncology; Preclinical Study; Proteomics; Receptor, Epidermal Growth Factor - genetics; Signal Transduction; Triple Negative Breast Neoplasms - drug therapy; Triple Negative Breast Neoplasms - genetics; Triple Negative Breast Neoplasms - pathology; Breast cancer; Metastasis; p63; Adhesion; EGFR; Invasion
• ISSN: 0167-6806; 1573-7217
• DOI: 10.1007/s10549-017-4216-6

Purpose
The basal-A subtype of triple-negative breast cancer is characterized by high levels of ΔNp63. Various functions have been proposed for p63 in breast cancer initiation and growth, and p63 mediates chemotherapeutic response in a subset of triple-negative breast cancers. We investigated the signaling pathways that are controlled by ΔNp63 in basal-A triple-negative breast cancer.
Methods
Human basal-A triple-negative breast cancer cell lines with ΔNp63α induction or inhibition were studied, along with primary human triple-negative breast cancer tissues. Proteomic, phospho-kinase array, mRNA measurements, and immunohistochemistry were employed.
Results
Global phosphoproteomics identified increased EGFR phosphorylation in MDA-MB-468 cells expressing ΔNp63α. ΔNp63α expression increased
EGFR
mRNA, total EGFR protein, and phospho-EGFR(Y1086), whereas silencing endogenous ΔNp63 in HCC1806 cells reduced both total and phospho-EGFR levels and inhibited the ability of EGF to activate EGFR. EGFR pathway gene expression analysis indicated that ΔNp63 alters EGFR-regulated genes involved in cell adhesion, migration, and angiogenesis. Addition of EGF or neutralizing EGFR antibodies demonstrated that EGFR activation is responsible for ΔNp63-mediated loss of cellular adhesion. Finally, immunohistochemical staining showed that p63-positive triple-negative breast cancers were more likely to express high levels of EGFR than p63-negative cancers, corroborated by in silico analysis of gene expression profiling data.
Conclusions
These data identify EGFR as a major target for ΔNp63 regulation that influences cancer cell adhesion in basal-like triple-negative breast cancer.