Cell Interactome: Good Neighbors or Bad Neighbors

We report an interesting finding that cellular distribution and interactions between neighboring cells modulate protein expression and localization. MCF7 breast cancer cells, which express ERb, were cultured in estrogen free medium. ERb exhibited a unique migration pattern that was dependent on cell density and proximity. This findings attest to a novel mechanism other than ligand-receptor one. Since cells were grown in conditioned culture media, the only factor influencing protein distribution is cell-cell proximity (cell-cell interactions). Thus, hormonal receptors may function independently from their ligand. in addition, physical intercellular interactions may function as a non-molecular factor inducing gene expression and activation.