A consortium of researchers have identified the gene expression patterns of breast cancer stem cells that remain post treatment with either chemotherapy or antihormone treatments. They report that this gene signature differs from those linked to the bulk of epithelial cells in the tumor.
“These patterns resemble expression patterns more closely associated with cells with a mesenchymal phenotype,” notes Jenny Chang, M.D., medical director of the Lester and Sue Smith Breast Center and senior author of the paper, which appears in the current issue of the Proceedings of the National Academy of Sciences. The paper is titled, “Residual breast cancers after conventional therapy display mesenchymal as well as tumor-initiating features.” GlaxoSmithKline took part in funding for this study.
The investigators say that the chemoresistant breast cancer stem cells have a tumor-initiating gene signature. This was not only more easily detectable in a newly defined breast cancer subtype called claudin-low but also enriched in human breast tumors after they had been treated with anticancer drugs that target hormone signals. They also found that genes associated with the mesenchymal cell phenotype were increased in breast tumors after hormone treatment.
“This study supports a growing body of evidence that there is a particular subpopulation of cells in breast cancer that may be responsible for disease recurrence, resistance to treatment, and perhaps metastasis,” Dr. Chang adds.
In the future, she says, the group will be looking at ways to use the gene signature they have identified to develop drugs that can combine with conventional therapy to eradicate all populations of cells within tumors.