Zeb1 Is a Determinant of EMT in Human MDA-MB-231 Breast Cancer Cells and M13-MDA231 Tumor Hybrids

Zeb1 is a well-known epithelial–mesenchymal transition (EMT) transcription factor and is highly expressed in aggressive cancers. Tumor hybrids, which were derived from fusion events between cancer cells and normal cells, such as macrophage and stem cells, can possess novel properties, such as enhanced metastatic activity. The role of Zeb1 was studied in M13-MDA231-6 and -13 tumor hybrids that were derived from spontaneous fusion events between MDA-MB-231-Hyg human breast cancer cells and M13SV1-EGFP-Neo human breast epithelial cells. The stable CRISPR/Cas9-mediated Zeb1-KO was correlated with re-expression of E-Cadherin in MDA-MB-231-Hyg-Zeb1-KO and M13-MDA231-13-Zeb1-KO cells, but not in M13-MDA231-6-Zeb1-KO cells. Similarly, the proliferation of MDA-MB-231-Hyg-Zeb1-KO in M13-MDA231-13-Zeb1-KO cells, but not in M13-MDA231-6-Zeb1-KO cells, was decreased as compared to non-edited cells. The migratory activity of Zeb1-KO cells was markedly reduced in transmigration and invasion studies compared to non-edited cells. However, MDA-MB-231-Hyg-Zeb1-KO cells and M13-MDA231-6-Zeb1-KO tumors only showed reduced migratory behavior in a scratch/wound healing assay, while M13-MDA231-13-Zeb1-KO exhibited enhanced locomotory activity. In contrast, no clear effects of Zeb1 knockout were observed on colony-forming capacity or CD44+/CD104+ expression. In summary, our data support the role of Zeb1 as a driver of EMT and cancer cell migration.