Associate Professor Virginia Commonwealth University Richmond, Virginia, United States
Introduction: : Collective invasion, the process by which cells move as a unit and are connected to each other via cell-cell adhesion markers, is an essential component of breast tumor invasion. Tumor cell clusters sense external stimuli that lead to cell protrusions or extensions that begin the collective invasion cascade, resulting in metastasis. While breast cancer cells express different cadherins, including E- (CDH1) and P-cadherin (CDH3), most studies have focused on investigating CDH1 and less is known about CDH3 during the metastatic cascade. Here, we investigated how external cues stimulate biased cell protrusions mediated by CDH3 and Laminin332 signaling.
Materials and
Methods: : To model collective migration, we used our previously designed ex vivo 3D microfluidic system and genetically defined primary breast tumor organoids derived from MMTV-PyMT mouse model to incorporate native tumor cell heterogeneity. Our models allow precise control of matrix architecture, controlled chemokine gradients, and controlled interstitial fluid flow. To investigate contributes of CDH3, we performed targeted knockdown with shRNA (shCDH3). Mechanistic studies were performed to understand how biased protrusions, CDH3, and laminin332 signaling are linked together.
Results, Conclusions, and Discussions:: In a controlled chemical gradient and aligned matrix cue, tumor cell clusters responded to the chemokine gradient with cell ruffling and protrusions in the direction of chemokine gradient. shCDH3 tumor clusters did not generate cell ruffles or protrusions in response to the chemokine gradient. We rescued invasive behavior in shCDH3 clusters through incorporating laminin332 in the tumor microenvironment, suggesting a feedback loop between laminin332 and CDH3 that is required for collective invasion. cells with Rho activator rescued cell protrusions. Our study demonstrates mechanical cues in the environment can dictate tumor invasion, and CDH3 has an essential function in successful development of cell protrusions associated with laminin332 signaling. Finally, our microfluidic models provide a new way to understand how chemokine gradients, fluid flow, and matrix architecture are interlinked to affect microscale interactions between cells and their environment.
