Np63 activates EGFR signaling to induce loss of adhesion in triple-negative basal-like breast cancer cells

• Published in: Breast cancer research and treatment 2017-06, Vol.163 (3), p.475
• Main Authors: Holcakova, Jitka, Nekulova, Marta, Orzol, Paulina, Nenutil, Rudolf, Podhorec, Jan, Svoboda, Marek, Dvorakova, Petra
• Format: Article
• Language: English
• Subjects: Analysis; Angiogenesis; Antibodies; Breast cancer; Cancer research; Cell adhesion; Cell adhesion & migration; Chemotherapy; Epidermal growth factor receptors; Epidermal growth factors; Gene expression; Immunohistochemistry; Kinases; Phosphorylation; RNA; Signal transduction; Tumor cell lines
• 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 [DELTA]Np63. 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 [DELTA]Np63 in basal-A triple-negative breast cancer. Methods Human basal-A triple-negative breast cancer cell lines with [DELTA]Np63[alpha] 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 [DELTA]Np63[alpha]. [DELTA]Np63[alpha] expression increased EGFR mRNA, total EGFR protein, and phospho-EGFR(Y1086), whereas silencing endogenous [DELTA]Np63 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 [DELTA]Np63 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 [DELTA]Np63-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 [DELTA]Np63 regulation that influences cancer cell adhesion in basal-like triple-negative breast cancer.