Background of chemoresistance of breast cancer with HER-2/gene amplification and/or overexpression

Results of the most recent basic studies on the cause of chemoresistance of breast cancer epithelial cells with HER-2 gene amplification and/or overexpression are presented. These studies, conducted in cell and animal models, demonstrate that dramatic proliferation of cells accompanying p185 protein (HER-2 gene product) overproduction leads, via the processes of clonal and adaptative selection of resistant tumour cells, to acquired chemoresistance. Therefore, in these cases, this resistance to chemotherapeutics is rather secondary, than connected primarily with HER-2 gene amplification. This can also mean that more aggressive chemotherapy can improve clinical response.

Both the newest and some older clinical papers are presented, which agree with the results of the basic studies as yet, and, analysed together, illustrate adequately the therapeutic problems in breast cancer.

In the paper, most recent methods are also presented of chemotherapy of epithelial tumours with HER-2 gene amplification and/or overexpression, including specific drug administration on molecular target, based on the REC (receptor enhancement chemosensitivity) strategy.