Development of Herceptin resistance in breast cancer cells

Abstract

Herceptin binds effectively to Her-2 on the cell surface of Herceptin-resistant cell lines and the level of Her-2 expression on the cell surface is not downregulated. Herceptin resistance is not due to downregulation of levels of AKT protein expression, although, phosphorylation of AKT is enhanced in resistant lines and could have a role in resistance. Resistance appears to correlate with the loss of nuclear expression of the cyclin-dependent kinase inhibitor, p27, as defined by immunofluorescence and flow cytometry studies and cdk-2 binding studies.