Mice lacking a particular enzyme have a significant delay in developing mammary tumors, and less progression to secondary lung cancer, according to a study to be published in the March 2007 issue of Nature Genetics. These results have implications for the treatment of human breast cancer.
The gene ERBB2 is overexpressed in approximately 30% of early-stage breast cancers in women, and a drug designed to inhibit ERBB2 activity (Herceptin) has had a significant impact on the treatment. Michel Tremblay and colleagues studied a strain of mice that typically develop metastatic mammary cancer as a consequence of hyperactive ErbB2. They found that deletion of PTP1B, an enzyme that is activated by ErbB2, resulted in a significant delay in the onset of mammary tumor development in these mice, and suppression of lung metastases. They went on to show that oral administration of an inhibitor of PTP1B resulted in a similar delay in the onset of cancer.
PTP1B is overexpressed in at least 70% of all breast tumors in women, although the significance of this has been unclear. The study by Tremblay and colleagues suggests that a therapy combining Herceptin with a PTP1B inhibitor in a sub group of women with breast cancer might be beneficial, although this will have to be tested in clinical trials.
Michel Tremblay (McGill University, Montreal, Quebec, Canada)
Abstract available online.
(C) Nature Genetics press release.
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