Interactions between αv-Integrin and HER2 and Their Role in the Invasive Phenotype of Breast Cancer Cells In Vitro and in Rat Brain.

Abstract

BackgroundWe tested the hypothesis that αv-integrin and the human epidermal growth factor receptor type 2 (HER2) interact with each other in brain trophic metastatic breast cancer cells and influence their invasive phenotype.MethodsClones of MDA-MB231BR human breast cancer cells with stable knock down of αv-integrin in combination with high or low levels of HER2 were created. The interactions of these two proteins and their combined effect on cell migration and invasion were investigated in vitro and in vivo.ResultsKnockdown of αv-integrin in MDA-MB231BR clones altered the actin cytoskeleton and cell morphology. HER2 co-precipitated with αv-integrin in three breast cancer cell lines in vitro, suggesting they complex in cells. Knockdown of αv-integrin altered HER2 localization from its normal membrane position to a predominantly lysosomal localization. When αv-integrin expression was decreased by 69-93% in HER2-expressing cells, cellular motility was significantly reduced. Deficiency of both αv-integrin and HER2 decreased cellular migration and invasion by almost 90% compared to cells expressing both proteins (PConclusionsαv-integrin interacts with HER2 in breast cancer cells and may regulate HER2 localization. The combined impacts of αv-integrin and HER2 influence the invasive phenotype of breast cancer cells. Targeting αv-integrin in HER2-positive breast cancer may slow growth and decrease infiltration in the normal brain.