RUNX2 and TAZ-dependent signaling pathways regulate soluble E-Cadherin levels and tumorsphere formation in breast cancer cells.

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TitleRUNX2 and TAZ-dependent signaling pathways regulate soluble E-Cadherin levels and tumorsphere formation in breast cancer cells.
Publication TypeJournal Article
Year of Publication2015
AuthorsBrusgard, JL, Choe, M, Chumsri, S, Renoud, K, Mackerell, AD, Sudol, M, Passaniti, A
Date Published2015 Sep 29
KeywordsAnimals, Blotting, Western, Breast Neoplasms, Cadherins, Core Binding Factor Alpha 1 Subunit, Doxycycline, Gene Expression Regulation, Neoplastic, Humans, Intracellular Signaling Peptides and Proteins, MCF-7 Cells, Mice, NIH 3T3 Cells, Protein Binding, Receptor, erbB-2, Reverse Transcriptase Polymerase Chain Reaction, RNA Interference, Signal Transduction, Solubility, Spheroids, Cellular, Transcription Factors

Intratumoral heterogeneity and treatment resistance drive breast cancer (BC) metastasis and recurrence. The RUNX2 transcription factor is upregulated in early stage luminal BC. However, the precise mechanism by which RUNX2 regulates an oncogenic phenotype in luminal BCs remains an enigma. We show that RUNX2 is predictive of poor overall survival in BC patients. RUNX2 associated with the TAZ transcriptional co-activator to promote a tumorigenic phenotype that was inhibited by knockdown of TAZ. RUNX2 increased endogenous TAZ translocation to the nucleus, which was prevented by inhibiting RUNX2. RUNX2/TAZ interaction was associated with ectodomain shedding of an oncogenic soluble E-Cadherin fragment (sE-Cad), which is known to cooperate with human epidermal growth factor receptor-2 (HER2/ErbB2) to increase BC growth. Neutralizing E-Cadherin antibodies or TAZ knockdown reduced the levels of sE-Cad in RUNX2-expressing BC cells and inhibited tumorsphere formation. RUNX2 expression also increased HER2-mediated tumorsphere size, which was reduced after treatment with the HER2-targeting agents Herceptin and lapatinib. These data support a novel role for RUNX2 in promoting an oncogenic phenotype in luminal BC in the context of TAZ, sE-Cad, and HER2. Using this signaling pathway to monitor BC cell oncogenic activity will accelerate the discovery of new therapeutic modalities to treat BC patients.

Alternate JournalOncotarget
PubMed ID26320173
PubMed Central IDPMC4695049
Grant ListI01 BX002205 / BX / BLRD VA / United States