Sauder CA, et al., 2014

Within the normal human breast are epithelial cells (cells that line the ducts), which sometimes have "phenotype plasticity", that is, the ability to change to adapt to their environment. This adaption may lead to metaplasia, which is the replacement of cell tissue with another kind not usually found in the breast. Metaplasia may lead to cancer, though it often is benign.

However, one form of triple-negative breast cancer, metaplastic carcinoma of the breast, is particularly aggressive. Scientists want to know why plasticity may respond incorrectly to the environment, prompting metaplasia and, sometimes, metaplastic carcinoma.

Scientists used normal tissue from the Komen Tissue Bank to examine these processes. They used three different tests: immunohistochemistry, or the use of antibodies to look for tumor markers; flow cytometry to look closely at the cells; and in vitro cell culture, a way to see how cells respond in a controlled environment. Each of these helped show how plasticity behaves in normal tissue.

In testing in the lab, all of the epithelial cells from normal tissue had the ability to differentiate in vitro into a variety of cell types. This ability often helps the body repair damage or remodel after change, but it sometimes goes awry. One type of cell mimicked that seen in metaplastic carcinoma of the breast, which the researchers think may be due to the tissue microenvironment.

Using normal tissue from the KTB, scientists used several kinds of tests to observe the process of plasticity. Previously, such testing used tissue samples from patients who already had experienced significant changes to their breast tissues. This study pointed researchers' attention to the tissue microenvironments as a possible answer to their initial question of why these cells change to eventually lead to metaplastic carcinoma. Future research may lead to studies on how altering the microenvironment may prevent those changes that allow cancer to form.