Novel Differentiation Therapy Approach to Reduce the Metastatic Potential of Basal, Highly Metastatic, Triple-Negative Breast Cancers

摘要

Low-grade breast cancer is associated with increased differentiation and reduced metastases, suggesting that reprogramming tumor cells to a more differentiated state could improve outcome. Utilizing a novel differentiation therapy approach, We have reprogrammed aggressive, basal, triple-negative Breast Cancer (BrCa) (generally with poor prognosis) towards a less aggressive phenotype by manipulating expression of the key mammary luminal differentiation transcription factor, GATA3. GATA3 is essential for programming undifferentiated mammary cells into a luminal subtype while myoepithelial/basal cells fail to express GATA3. Significantly, GATA3 expression is highly correlated with the luminal, more differentiated BrCa phenotype. We hypothesized that ectopic expression of GATA3 in metastatic, basal BrCa cell lines will reprogram them to a more differentiated, less metastatic phenotype. Over-expressing GATA3 in human basal-type MDA-MB-231 (231-GATA3) breast cancer cells induced significant morphological changes in 2- and 3-D cultures compared to control cells (231-Empty). 231-Empty cells maintained a spindle, elongated morphology, while 231-GATA3 cells became rounded and larger. In 3D Cultrex, 231- GATA3 cells appeared smaller, more organized, and rounded compared to 231-Empty cells. Microarray profiling of 231- GATA3 vs. 231-Empty cells revealed gene expression changes associated with increased adhesion, reduced extracellular matrix remodeling factors and reduced metastasis. Western blot confirmed reexpression of E-cadherin and an increase in cytokeratin-18 in 231-GATA3 cells, indicative of a more luminal phenotype. 231-GATA3 cells showed reduced LOX expression by real time PCR and knock down of GATA3 in the luminal BT474 cell line increased LOX expression. This demonstrates for the first time that GATA3 is an important differentiation factor that reduces the metastatic potential of MDA-MB-231. Ultimately, t.